conventional oil recommendation pathfinder

[suzonka]

I have an 03 Le pathfinder automatic 6 cyl VQ35D engine , the owners manual says never use synthetic oil . so I have been using conventional oil changing with a filter every 4000 miles. what I;m down to is using 2 brands Mobile 5000 or Quaker state 10 W 30,
so which is a better of the 2 oil's mentioned or should I completely change brands . Im looking to get the high miles out of this good running engine so far at 109,000 miles on it,

[barnaclebob]

Personally I'm not sure I believe the no synthetic recommendation. Chemically I thought the difference is that the strands of hydrocarbon molecules were more controlled/engineered in synthetic oils. Other cars with the 3.5l engines do not have this recommendation.

[Hawairish]

The owner's manual doesn't say "never"; it just recommends using a conventional oil over a synthetic. Even then, your synthetic oils will carry the same API certification marks that the manual suggests.

Personally, I'd look into some "oil myths" and leave it at personal preference. This is a highly subjective topic. I mean, what's the basis for determining if one oil is better than another? Price? Reviews? Opinions? How will you measure quality?

The most important thing is being diligent about changing the oil and maintaining the engine, whatever the "right" oil, budget, maintenance schedule, and intended use is for your vehicle.

[yeldogt]

At 4k oil changes -- anything will work. Even the cheapest oil today is better then the stuff back in the late 90's

I have had problems with synthetic oil in the 3.5 Nissan V6 -- synthetic oil does not thicken when cold .. all three of my pathfinders and my ultimata dripped oil with synthetic.

I use the blended or high mile conventional oil in my pathfinders -- 10w/ 30 -- with a 7.5k change interval. All have gone over 175k with no engine issues.

When you change at 4k -- Im sure it is still clean ... mine at 7.5 is clean .. I feel guilty?

[patqx4]

At 4k oil changes -- anything will work. Even the cheapest oil today is better then the stuff back in the late 90's

I have had problems with synthetic oil in the 3.5 Nissan V6 -- synthetic oil does not thicken when cold .. all three of my pathfinders and my ultimata dripped oil with synthetic.

I use the blended or high mile conventional oil in my pathfinders -- 10w/ 30 -- with a 7.5k change interval. All have gone over 175k with no engine issues.

When you change at 4k -- Im sure it is still clean ... mine at 7.5 is clean .. I feel guilty?

I must say I agree with this line of thinking. I used to change oil in cars past every 5k (km). The oil still looked almost like new and it felt very wasteful. Now I change it every six months, using conventional oil, its usually at least 10,000km I think and the oil still looks pretty good, not black. I've pulled the dipstick on lots of cars and seen tar-black oil. Even running extended intervals my oil does not approach that. Ymmv.

[Hawairish]

The last two comments are inline with something I thought about putting into my first response...each oil change really sees about 1%-2% of the engine's life assuming it reaches 150K-200K. You'd never know the difference one oil change makes (unless you can't close the hood because you didn't remove the can...Tommy Boy reference). And my thinking is, assuming you used the same brand oil for the life of the engine, you could come to two opposite conclusions:

1. The oil caused the engine to fail prematurely
2. The oil caused the engine to last longer

But, you'd never know. Don't forget that the filter is the other part of the equation, and is also a subjective decision (though I'd argue that it is more important than the oil decision if you plan to use the filter longer, such as with a synthetic). I've used the same "crappy" Fram filters almost exclusively on a 17-yo Frontier that now has well over 200K miles...it must be doing something right.

It's all about maintenance. I actually only change my oil twice, maybe thrice, a year. I don't drive the truck frequently, I live in a climate that doesn't warrant 5W, and use synthetic because it can resist degradation for a longer period. And when it comes down to it, I buy whatever is on sale at the time.

[suzonka]

At 4k oil changes -- anything will work. Even the cheapest oil today is better then the stuff back in the late 90's

I have had problems with synthetic oil in the 3.5 Nissan V6 -- synthetic oil does not thicken when cold .. all three of my pathfinders and my ultimata dripped oil with synthetic.

I use the blended or high mile conventional oil in my pathfinders -- 10w/ 30 -- with a 7.5k change interval. All have gone over 175k with no engine issues.

When you change at 4k -- Im sure it is still clean ... mine at 7.5 is clean .. I feel guilty?

Yes you got it its the dripping , as far as I could look up in oil myths and tech notes they say the seals have to be made out of a material that can with stand the cleaning action of the high detergent in synthetic oils .

[yeldogt]

I'm more inclined to believe it's simply a mater of the seals expanding along with the metal surfaces to keep all tight and drip free -- as the engine cools and the spaces expand the more fluid synthetic oil is able to weep pats the seals ... I never got much ... but I would get a drip after the car sat overnight.

The high mile oil has additives to expand the seals .... most modern oils have detergents.

I use synthetic in the majority of my cars -- it's always going on sale -- for a few extra dollars .. why not. I always use it in the ones that are not driven much -- synthetic can stay in the engine for 2 years vs 1 for traditional if you follow the normally thought on this. I always use a good filter -- normally the OE .. with all the online dealers getting the OE is cheap and easy.

[atraudes]

In response to your original question: it probably really doesn't matter. Like others have said, your diligence is probably way more important. But given the choice between those two, I'd go with the the Mobil.

You're right that the matter of synthetic vs. conventional is still up for debate and ultimately personal experience (you'd think they'd be similar enough!). However, I've seen a number of accounts here of people with 03's and 04's burning oil at a ridiculous rate when using synthetic but not with conventional (or, at least, to a much lesser extent). That combined with the manual's recommendation means I'd stick with conventional.

According to the owners manuals, for '01 and '02 synthetic is fine ("Mineral based or synthetic type oils may be used in your NISSAN vehicle."). For '03 and '04, it's not ("NISSAN does not recommend synthetic type oils but recommends mineral based oils.").

Some excellent threads off the top of my head on the topic, FWIW:

post5793504.html
best-oil-for-a-120k-mile-engine-t487993.html
vanishing-oil-where-you-sneakin-off-too-t604011.html
post6627485.html

[barnaclebob]

We'll I just filled my 2001 with Valvoline synpower for the first time. The oil before that was maxlife synthetic blend. Before that was Dino from Midas.

[Buzzman]

2 thoughts: First, don't switch back and forth between regular oil and synthetic. Stay with one or the other for the life of the vehicle.
Secondly, switching to synthetic should be done early in the life of the engine.
I would not switch over to synthetic on a high mileage car that has run conventional oil all it's life.
I switched to Mobil 1 right after I bought my truck. It was a year old and had about 25,000 miles on it.
I've run with that ever since, and still have no leaks or oil burning issues.

[AlanAZ]

I have had problems with synthetic oil in the 3.5 Nissan V6 -- synthetic oil does not thicken when cold .. all three of my pathfinders and my ultimata dripped oil with synthetic.

I've used M1 0W40 for the past 3 years, 7K mls OCI, now at 120K miles, and no leaks. It does use about 1 qt of oil during the 2nd half of the interval, but also used about the same with conventional with shorter OCI.

[barnaclebob]

Still no issues from the switch to synthetic here. I just remember that I had a volvo that developed a slow oil leak, only used conventional. Eventually the oil leak stopped on its own... The point is that correlation doesn't mean causation.

The opinion on the bobistheoilguy forums is that saying not to switch to synthetic on a high mileage car is a myth from when synthetics first came out and didn't have the right chemistry to keep seals in good shape.

[yeldogt]

Switching back and forth is not going to cause any problems. When an engine cools it's not unusual for this to be the only time it leaks --- one of my pathfinders would drop a quarter sized spot of coolant on the driveway whenever it was parked late in the evening hot and the temp was especially cold ..... it did it for years and we could never track it down.

The same with the oil --- conventional oil thickens a bit when cold. Synthetic does not Another common leak point is the valve covers on some cars.

The high mile oils contain a product to swell the seals -- It's not something I want to use.

[AlanAZ]

I've used M1 0W40 for the past 3 years, 7K mls OCI, now at 120K miles, and no leaks. It does use about 1 qt of oil during the 2nd half of the interval, but also used about the same with conventional with shorter OCI.

Further, I wanted to use a 0w oil for a time to clear the small oil passages in the variable valve timing mechanism, and the hard to replace PCV valve. And I'm replacing the oil filter (one designed for synthetic oil use - in this case Purolator Synthetic) half way through the oil change interval (3.5k mls) to capture sludge that's clearing from prior conventional oil use.

http://www.aa1car.com/library/variable_valve_timing.htm

Only when it starts to drip oil, will I switch to a higher viscosity high-mileage synthetic oil.