Synthetic oil is obviously better and I am considering using redline. However after talking to someone last night that swore by Amsoil I decided to do a little searching. After looking through numerous forums and many sites trying to find real meat on the question I decided to just come out and ask the questions I want answers to.

My car is relativly low mileage 22k. Should I do a flush on it before putting in a synthetic oil? Would you give me the same answer if I told you that I bought the car used and have no clue what its had in it before?

Second question, is there really a difference between two brands of the same oil? ie Amsoil 5w30 vs Redline 5w30 vs Royal Purple 5w30.... you get the picture.

Thank you that is all I can think of at the moment but I'm sure I'll think of something later.

I use Mobil 1 Synthetic 0W-40 for a good wide range of temperatires and overall goodness - switched after an initial 7500 miles of 5W-30 and 5W-40 dino oil. I don't have any experience with Amsoil or Redline or Royal Purple, but others here like them too.

Yes, there can be a difference between different synthetic 5W-30 oils, in the amount of additives the particular manufacturer happens to use. In most cases, this will not matter as much as changing the oil often.

Finally, you do not need to do a flush prior to the change. The oils will blend just fine. Although an engine flush will not hurt per se.

And, yes, I think I would give you the same answer with a used car ... as long as the previous owner provably did oil changes often enough - even with a decent (as opposed to excellent) dino oil. If not provable, I would not buy the car in the first place!

Z

no flush needed

your best picks are going to be as follows:M1, or Redline, both are great and cant lose with eitherAmsoilRP

There are large differences between redline, amsoil, etc...even for the same grade (5w30).

"Second question, is there really a difference between two brands of the same oil?"

You're asking the differnece between brands of the same oil WEIGHT, not "same oil"....

Redline and Mobil1 are currently the only oils i would roeccomend to you. I'm running redline fuilds throughout my 350Z, with less than 13k on the clock. It's expensive, but worth every penny.

royal purple is ****, and to me amsoil ius overhyped and overpriced, espspecialy compared to mobil1.

Redline comes brom better base stocks than mobil1, and has better film strength, so I would run that if you can afford it..otherwise mobil1 is the rockstar.

-Chet

http://www.bobistheoilguy.com

Check out the VOA section.

An oil really wants to be nice and high in antiwear additives. Being Molly, Zinc and Phosphorus.

Most of these additives (bar molly) are cat killers, my understanding is the latest api meeting oils remove these nice antiwear additives in favour of extending the life of your cat.

I believe Motul 300v is a better oil than redline.1. Motul 300v is a 100% Ester based oil where as Redline is a PAO oil.2. Motul 300v contains higher levels of molly3. Motul 300v here in AUS is cheaper than Redline.

Synthetic is a waste of money. In everyday use, I have not been able to detect any improvement in performance of the engine nor have I been able to increase the change interval. The synthetic gets dirty just as fast as dyno oil.

The most important thing is regular oil changes.

yellow wrote:Synthetic is a waste of money. In everyday use, I have not been able to detect any improvement in performance of the engine nor have I been able to increase the change interval. The synthetic gets dirty just as fast as dyno oil.

The most important thing is regular oil changes.

No one uses synthetic oil because it "gets dirty slower." They use synthetic to reduce engine wear.

There are situations where regular dino oil is the better option...but not because synthetic is a waste of money.

Here lets get a few things straight since everyone seems to be a little misinformed and please don't take that personally.

"Are there differences between different brands (of the same rated oil)?" Absolutely! Every manufacturer uses their own proprietary mix of additives. In addition to that, different base stocks are used for organic oil, and COMPLETELY different bases are designed for synthetic.

The ratings on a bottle can be deceiving. 2 bottles of 10w-30 just are only the same in that they both meet the wide spec range for that class of oil.

Here is the true benefit in synthetic over organic oil. Synthetics are designed to keep your engine from wearing. Organics are like the civic sedans trying to beat skylines by adding headers and an intake.

You're taking crude organic oil. Refining it and refining it and repeat that phrase another 20 times and you'll get half way there. Then adding phosphorus, zinc, and a multitude of other things to make it 1) pour at cold temps (the first number in 5w-30), not break down from the 30 weight down to a 20 weight or less, detergents so it doesn't sludge and varnish your engine and the list is probably in the area of 3 dozen factors to make the crude oil worthy of being in your engine.

Synthetics don't have half as many additives, because they are chemically designed (not chemically modified) to protect your engine.

As far as additives hurting your CAT...WRONG! The only time those additives get to your CAT is if your burning oil in which case, it's not the additives fault, it's something else that's wrong.

One thing to consider when changing over to synthetic is that there is a generally accepted practice to stick with synthetic once you've changed. My understanding is that the synthetic creates a barrier that the organic can't breach and makes the organic useless after going back and forth. I DON'T KNOW THIS PART FOR A FACT!!!

As far as prolonging your drain period...Flush your engine, go with a high grade synthetic like amsoil, add on a high effeciency filter like a K&N or amsoil and now your recommended change interval has been extended to 15k miles. 35k on some applications. You'll have to check the amsoil site for their recommendations.

Do a google for "Engine oil bible" It's a long e-book, but the information is priceless.