Synthetic oil or regular oil

[Driving Instructor]

My car is about to hit 100 000kms. Today 99 386 kms.

I change my oil religiously no more then 6000 kms. I found that I have some engine noise at start up so I was thinking of using Synthetic oil. My understanding is it gets to areas faster then conventional oil and it last longer.

So conventional oil or synthetic oil?

Is it true that you can go longer between oil changes when you use Synthetic??

Any feedback would be appreciated!

[feloniousmonk]

It's not quite as black and white as your poll suggests.

Generally, yes, you can go longer with synthetic. If you're changing every 6000km (3.7k miles) then you don't really need to spend the extra money for synthetic... unless you drive hard, in very hot conditions, or do a lot of short trips with frequent shut-off and starts. Whatever you choose, try running a good fuel injector cleaner (like Chevron Techron) before you switch. Pour one bottle into a near empty tank, fill then drive until that new tank of gas is gone then do a full oil change.

If you decide to stick with conventional, you may want to consider using a different brand as some brands have a better detergent package than others. Castrol is pretty good.

Change the spark plugs and plug wires (general tune up) if you haven't already. At 100,000 km it's probably due.

[XterraVersa]

If your going to change it every 6000km then stick to a good dyno oil, but 0w-30 in the summer. I ran 0W-30 Mobil 1 syn & didn't have the start-up noise it had with the OEM 5W-30.

If you switch, try doubling your change interval, but get a good oil filter.

[BBISHOPPCM]

Mostly good advice, but the injector cleaner is nearly useless (snake oil) as all gasolines manufactured today have excellent detergent packages in them (stick with name-brand fuels like Mobil (or Esso), Texaco, Shell, etc. As for the plug wires, the Versa uses a coil-over-plug system, so there are no plug wires to replace. The plugs are good for 100,000 miles, but should be removed by the 50,000 mile mark and re-installed with an anti-seize compound. Feloniousmonk is right; synthetic is a good idea if you run over the 3,000 mile mark regularly between changes, and if frequent startups are part of your daily driving habits. A good quality conventional oil is probably a better alternative (Castrol, and higher-end Mobil oils, or brands like Amalie, etc).

[fjwagner]

http://www.bobistheoilguy.com is a good resource.

there are as many opinions about oil brands, intervals, type as their are members of this forum. I run ~5000 miles or so on dino oil, but I verified that interval by sending oil in for analysis that confirmed I still had good oil with proper properties at that interval. I run ~10 k miles on two BMW's on synthetic. I use only Mobil 1 synthetic and Exxon Superflo Dino but I work for them, so feel compelled to do so. Any of your major well known brands are good.

[frankoV]

It's also been suggested that once you've run dyno for a good long time [100K] you should stick with it, as synthetic may harm the seals

[XterraVersa]

There is nothing wrong with switching. I switch the Xterra to synthetic to Mobil 1 at 75k and no problems 2 years later.

The switch may have been valid for older cars, but these new modern engines use smaller seals that are less prone to failure.

[fjwagner]

It's also been suggested that once you've run dyno for a good long time [100K] you should stick with it, as synthetic may harm the seals

My understanding is that is not really valid. I switched from dino to synthetic at 120 k on our 95 318i and no problems. Everything I have read indicates no problem either. I think that the seal issue is an "old wives tale". Fred

[Driving Instructor]

Thanks for all the feed back.

One thing I want to clear up is that I am thinking of switching to Synthetic. And I was hoping that I can run 10000 kms between oil changes instead of 6000 kms. I have a van with 398 000 kms (dodge). I bought it with 360 000 kms and the owner always ran synthetic. The engines runs like a charm!

I do the major of my driving in-town and lots of stop and go.

I was planning to run Castrol Synthetic oil(already bought the oil on sale 40% off reg price)

Again, any more feedback would be greatly appreciated!

[blockmachining]

I'm being lazy here, but I have copied and pasted a few of my previous replys regarding oil type and change intervals. The last few paragraphs starting with sooner4X4 were in response to his disagreement with some of my statements. I hope this helps

I changed over to synthetic oil when the car had 500 miles on it. The synthetic oil does not have polymers in it like the old dinosaur oil does. Its these polymers that cause the black gue to build up inside an engine. This black gue eventually reduces the size of your oil galley passage ways inside the engine. When regular oil comes out of the ground, it is not a multi grade oil. It is a straight weight oil...say 30 weight or 20 weight or whatever that particular oil field is producing. The polymers are added to make it 5W-30 or whatever you need. As far as the interval between oil changes....unless you drive crazy or in extremely dusty conditions, just change the synthetic oil every 7,500 miles as the owner's manual states. Now if you are using the dinosaur oil, change the oil more often. The reason is that the polymers are being deposited throughout the engine which is gradually changing the weight of the oil as you drive. Dinosaur oil also tends to "float" the small metal chips that occur as any engine wears over time. When these chips float, they again are attaching to the "sticky" polymer molecules in the oil. Again, the very best thing you can do for the longvity of the engine is switch over to synthetic oil.

You are welcome. The oil filter will be just fine to the 7500 mile mark. With only 11,000 miles on your engine, the polymers have not set up large deposits in your engine as of yet. You will not have an issue switching over to synthetic oil.People in excess of 100,000 miles, though, would need to be a little concerned and take a few special actions. In particular, when you change the oil over to a synthetic oil on a high mileage engine, the deposits in the oil galley and on the top of the head have a tendency to start washing away. When this happens, this gue can get caught in an oil jet and block that jet. Also, the oil filter might clog up with the newly released gue. So, on a high mileage engine switching over to synthetic oil for the first time, it would be adviseable to replace the oil filter after the first say 1500 miles to prevent the oil filter clog from happening. As far as the oil jets are concerned, not much can be done here. You'd be rolling the dice. I have a 1948 Dodge truck that was my grandfathers. He put whatever type of oil he could find in it. Obviously, it is a high mileage engine. Due to this, I continue to use the old dinosaur oil in it. If I overhaul this engine in the future, the oil that will be used from that point on would be synthetic.

Yes, it will be very happy. I used that oil in my 90 Nissan 300ZX twin turbo. No problems whatsoever, even with the two very hot operating turbos.Something I want to mention; also, and I see it discussed in several different forums on the net.....How often should you change your oil. I worked for Nissan's powertrain division in Tennessee. We had several dynos running at any given time testing our engines for assembly or design defects. We would run these engines to an estimated 110,000 miles at 200 rpms past the red line. The engines, especially around the exhaust manifolds and exhaust pipe would be glowing red hot. We would not change the oil until somewhere around approximately 55,000 miles. This is the point at which the oil would start to break down and the pressure would drop. There is absolutely no reason to change your oil any sooner than the recommended 7,500 mile mark unless you are racing your engine, your engine is beginning to come apart (bearing or other material is being found in your filter and or oil pan, the car is going to sit for 6 or more months without being driven, or running in constant dirt or blowing sand environments. The reason the time factor is important is because some of the by products of a combustion engine gets into the oil. The oil can become a little bit on the acidic side and eat into your engine parts, especially the bearings and cylinder walls.

As far as cost goes......Consumers using dino oil who change their oil every 3,000 miles end up spending more money than the consumer who uses the synthetic oil and changes their oil every 7,500 miles. Lets say dino oil cost $2.39 per quart, a quart of synthetic oil $5.00, and a good name brand filter $4.00. So for a car that uses 5 quarts of oil, it would cost the dino oil consumer to drive 7,500 miles and change the oil 2.5 times more money than the synthetic oil consumer....Lets see..... [(5 X $2.39 quarts of oil) + $4.00 filter] X 2.5 changes = $39.87. Now the consumer who uses the synthetic oil would pay [(5 X $5.00 quarts of synthetic oil) + $4.00 filter] X 1 change = $29.00.....a savings of $10.87 for the good stuff! And this is if you do the oil change yourself. If you are paying someone else to change your oil, then the savings are even greater.

As sooner4X4 mentions, yes, dino oil goes to a refinery where the oil is refined into many different products. I was not trying to detail what happens to oil once it comes out of the ground. As far as the dino oil that goes in your engine is concerned....it is at the refinery where the polymers are added to make it a multi weight oil...5W-30, 10W-40 or whatever. Its these polymers that build up in your oil galley passageways, on top of the heads, around your oil jets, and many other locations within your engine.In addition, as sooner4X4 states, dino oil will not necessarily make your engine fail before you get rid of it, but I'm here to tell you, and this comes from having responsibility (my assignments over the years consisted of assembly of engines to the machining of the heads and block) for the building and testing of over 6.6 million engines, synthetic oil is better for your engine. When you tear an engine down that has used synthetic oil over it's life, there is less wear on the cylinder walls, less wear on the bearings, oil jets and oil passageways are completely clear of any blockages, and less metal floating around in the oil or in the filter. This is not just a visual observation or opinion, but measured and recorded. In addition, we used an oil analysis program which determined what was floating around in the oil and what had been captured by the filter. This program would also tell you what type of metal it was and what part of the engine was wearing.

Last, but not least....the statement about when oil breaks down and things don't add up. Again, from first hand experience....In our dynos, when a Nissan engine (we tested the 5.6 liter V8s, the 4.0 liter V6s, the 3.5 liter V6s and the 2.5 liter I4s, the dino oil (Yes, we would use dino oil....it was cheaper. We used Texaco oil.) would begin to break down around 50 to 55,000 miles and the oil pressure would start to drop. An alarm would sound which would reduce the engine rpms from 200 rpms above red line to idle and then it would shut the engine down. We would go into the room where that particular engine was located and change the oil and filter. We would then start the engine back up and everything would be back to normal. Thats all I'm trying to say. I certainly can't predict when an oil (or even different brands) will begin to break down on your engine out on the road. When I was in the Air Force, we tested several oils that could be used in the 40,000 rpm jet engine main bearings and found Vavoline oil was the best for resistance to break down.

As far as full of misinformation, take that with a grain of salt. I'm just sharing with you my experiences over many years dealing with Nissan engines. Good luck and I hope you have many, many years and miles of happy service with your Nissan.

[frankoV]

fjwagner and XterraVersa: thanks for the info. And thanks for not attacking the poster for his post.

[scooterbob]

A good quality oil filter is much more important than normal or synthetic oil. You need to make sure the filter has a built in check valve, which helps the oil get to the motor much faster in a start up. The factory Nissan filter has this feature, as do many others. Getting a cheap filter without this feature can potentially harm your motor over time and also probably not filtering the best either. If you are considering putting more miles (km) between oil changes then this plays an even more important roll. Synthetic oil with a good quality filter is a win win.
Modified by scooterbob at 12:28 PM 7/20/2008

[feloniousmonk]

As for the plug wires, the Versa uses a coil-over-plug system

Shows you how many times I've looked under the hood since I got the V 3 months ago. It's been trouble free, haven't had much reason to look other than filling the washer fluid. Different story with the other car.

The thing about switching to synthetic after 100k km being a bad idea is nothing more than a myth. In most cases the seals have already gone bad due to age but the leaks were clogged up by sludge formed from infrequent and low quality conventional oil. When they switch to synthetic, the detergents in the new oil dissolves the sludge and viola, oil leaks. Those uninformed immediately blame the problem on the new oil when in reality it did them a favor by letting them know it's time to change the seals. So next time any of you see someone blaming synthetic for oil leaks, pass this bit of info along and keep the nonsense from spreading.

[fjwagner]

I found that I have some engine noise at start up so I was thinking of using Synthetic oil.

forgot to comment on this. Valve clatter at start up in the winter on our old 318i was the main reason I switched to synthetic in that car and lo and behold, almost all the clatter went away. You are right in that the synthetic oil gets into the nooks and crannies much quicker. Fred

Modified by fjwagner at 1:45 PM 7/20/2008
Modified by fjwagner at 2:06 PM 7/20/2008

[feloniousmonk]

Quote »forgot to comment on this. Valve clatter at start up in the winter on our old 318i was the main reason I switched to synthetic in that car and lo and behold, almost all the clatter went away. You are right in that the synthetic oil gets into the nooks and crannies much quicker. Fred[/quote]And the reason for that, based on what the Pennzoil engineers have told me when I worked with them, is the molecular strands are more uniform... like many uniformly sized micro ball bearings as opposed to conventional which is less uniform and don't get into tight spots as easily because the larger strands can actually block passage of their smaller comrades.

[Shad0wXCalibur]

I use synthetic just because it's synthetic and this city is a lot of stop and go. Also allows extended drain intervals. It's good to use if you drive in really cold weather, too. Even 5w-30 conventional can get a little thick if it's cold enough. And for the filter, I use Wix.

[hiimjered]

The thing about switching to synthetic after 100k km being a bad idea is nothing more than a myth. In most cases the seals have already gone bad due to age but the leaks were clogged up by sludge formed from infrequent and low quality conventional oil. When they switch to synthetic, the detergents in the new oil dissolves the sludge and viola, oil leaks. Those uninformed immediately blame the problem on the new oil when in reality it did them a favor by letting them know it's time to change the seals. So next time any of you see someone blaming synthetic for oil leaks, pass this bit of info along and keep the nonsense from spreading.

So switching still makes the seals start leaking, not because it destroys the seals, but because it cleans them. Still not a good idea on an older, high-mileage engine unless you are prepared to do a top-end rebuild. On a lower-mileage vehicle, synthetic is definitely better. I've seen engines with over 30,000 miles that still had honing marks on the cylinders, so I know the synthetic oils work very well. I would just be wary of switching in an older vehicle.

[srellim234]

I have a related question.

How long is it safe to leave the synthetic oil in if you replace the filter and whatever oil comes out with the filter every 7500?

[fjwagner]

I have a related question.

How long is it safe to leave the synthetic oil in if you replace the filter and whatever oil comes out with the filter every 7500?

not sure why you would not go ahead and change the oil at that time too. The incremental time to drain the oil and fill is not that much more. To make your plan work, you would need then to wait until 15 k to change the oil and the filter and most would likely agree that 15 k is too long. If you wanted to save some money on oil, then do a 5 k filter change and a 10 k filter/oil change. The synthetics are designed to go that long unless you do all stop and go driving. Fred

[srellim234]

That's kind of what I was asking. Will the synthetic last 15k miles as long as the filter is replaced? At what point in time does the synthetic start to break down?

[feloniousmonk]

That's kind of what I was asking. Will the synthetic last 15k miles as long as the filter is replaced? At what point in time does the synthetic start to break down?

As mentioned already, how long it lasts depends on a lot variables. How hard you drive the car. How frequently you shut down and start the car. Enviromental conditons, temperature extremes and how dusty the air is.

15k is far too long, IMHO for any kind of oil. If you're a retiree and don't drive the car much, then you can probably make it stretch that long. Not a chance I would take. Just because you can, doesn't mean you should.

Some manufacturers, like BMW, recommend 15k mile intervals because they offer free service for the first few years of ownership. Since they are picking up the tab, which is figured into the sticker price for the car, they want to maximize profit by minimizing expenditure.

[fjwagner]

That's kind of what I was asking. Will the synthetic last 15k miles as long as the filter is replaced? At what point in time does the synthetic start to break down?

I would not recommend that. If you want to take a scientific approach, run synthetic for 10 k and send it in to one of many companies that do oil analysis to get real data on the condition of your oil at that point. I would not recommend running 15 k without analysis that gave you real data versus opinions. Blackstone.com is one such company.

[repind39]

You have 100,000 KM (about 60k miles?) on the engine thats been using conventional and you want to swithc to synthetic? Not sure if anyone mentioned this but usually once you've been using conventional for like 20k miles its a good idea to stick with it for the life of the car. Synthetic oil is more slippery and tends to sneak past engine seals that have been "soaked" in conventional oil... I would just stick with regular oil with regular interval changes at this point and hope that the noise you're hearing isnt anything serious because if it is synthetic oil isn't gonna do much.

[fjwagner]

You have 100,000 KM (about 60k miles?) on the engine thats been using conventional and you want to swithc to synthetic? Not sure if anyone mentioned this but usually once you've been using conventional for like 20k miles its a good idea to stick with it for the life of the car. Synthetic oil is more slippery and tends to sneak past engine seals that have been "soaked" in conventional oil... I would just stick with regular oil with regular interval changes at this point and hope that the noise you're hearing isnt anything serious because if it is synthetic oil isn't gonna do much.

this issue has been discussed within this thread already and the issue you describe is not really an issue but what I call an "old wives tale". I switched at 120k and have been going 40 k with synthetic and no problems but quieter valves at start up.

[scooterbob]

I agree with fjwagner. I would change the synthetic oil every 10,000 miles and the filter (good quality) at every 5,000 miles. You can maximize your oil changes this way, and the synthetic should be well within normal operating life.

Also mentioned, it depends greatly on driving conditions. From what you have explained of your situation, you should be fine at this interval. If there's any doubt, have an oil analysis done to confirm everything is okay at this interval.

[DejaWiz]

Which fully synthetic passenger car motor oils contain Moly? I'm interested in switching to one so I can get the benefits of the coating early on in my engine's life.

[repind39]

this issue has been discussed within this thread already and the issue you describe is not really an issue but what I call an "old wives tale". I switched at 120k and have been going 40 k with synthetic and no problems but quieter valves at start up.

There is way too much inconsistancy on the effects of changing from conventional oil to synthetic, to simply brush it off as an "old wives tale" is the same as being 100% sure that changing to synthetic is bad... I heard that changing to synthetic is bad from a BMW tech, then I heard the opposite from another tech.... etc, all the sources I would consider credible so its tough to say whose right. I was just simply pointing out to the OP somethign to consider in case he didn't know.

[sooner4x4]

As usual, plenty of different opinions whenever oil is discussed. Reading through the thread several people warn that waiting too long to switch may cause problems due to a flushing of the engine of built up deposits. At the risk of having my comments taken out of context by blockmaching again with his creative use of cut and pasting, I will offer the following.

In your original post, it was stated that your normal Oil change interval (OCI) has been 6000km or approx 3600 miles. That frequent OCI probably kept your engine pretty clean, minimizing the potential for a lot of build up to have occured in 100,000km (60,000 miles).

While I currently don't run synthetics in my four vehicles, I do believe synthetics have their place;

-If you live up north with plenty of below zero mornings. Synthetic oil typically has way better cold weather properties than conventional oil.-If you do a lot of stop and go driving, short trips, for example if you used the car as a driver's ed car.-If you drive like a maniac running the engine at redline often.

It sounds like at least two of these conditions occur for Driving Instructor. Make the switch.

[Driving Instructor]

It's a go, I will be running Fully synthetic oil, CASTROL.

With only 100 000 kms (60 000 miles), I am confident the change over should not negatively affect the seals. It comes out nice and gold when the oil is changed.

I will keep you guys up to date!

Thanks again and this forum rocks!Gerry

[Shad0wXCalibur]

German Castrol is full synthetic. The other synthetic Castrol is just hydrocracked super refined dino oil.

It's a go, I will be running Fully synthetic oil, CASTROL.

With only 100 000 kms (60 000 miles), I am confident the change over should not negatively affect the seals. It comes out nice and gold when the oil is changed.

I will keep you guys up to date!

Thanks again and this forum rocks!Gerry