I only find the Motul 300V in 5W30 or 15W50. Are you Motul guys using one of those, or are you sticking with the 8100 X-Cess 5W40?

xtn I voted Amsoil

I'm surprised at the number of responses for Castrol Syntec. It's known to be a less than pure synthetic and yet a number of you are using it and actually seeking it out.

To each his own...
Hi. Only because this is what the dealer puts in for the 1st service. I do understand this is not 100% synthetic. I just has my first service yesterday. For my future oil changes I will do them myself so even though I said I will use Castrol Syntec I am still open for what oil I'll actually settle on. It will have to be 100% synthetic in the 5w-40 grade. That's fore sure. So please keep posting everyone, I am all ears. The answer is simple: the best oil is whatever type of synthetic is readily available at your local stores. Oil-related failures in modern cars are very, very rare. I believe that any synthetic would be adequate to get the car to 150k, 200k, maybe even more. I only find the Motul 300V in 5W30 or 15W50. Are you Motul guys using one of those, or are you sticking with the 8100 X-Cess 5W40?

xtn
Our distributor:
http://www.turbolubricants.com/products_racing.php

Haven't bothered to look for it yet, but had planned to call him to see who stocks it locally. It's a carry-over from the bikes with me - due to some pretty brutal lubrication requirements.

I'll have to decide between 300V and 8100 soon as I'm coming up on a change - verdict is still out here.

The truck still gets Mobil 1 though.

FWIW, I'm no fan of Redline. FWIW, Redline is less susceptible to high temperature degradation than either of the Motul oils. HTHS for Redline, Motul 8100 and Motul 300 V are 4.6, 3.92, and 4.51 cp (all for 5W-40).

HTHS for Amsoil, Mobil 1 and Havoline are 4.2, 3.6, and 4.1.

I really like redline, but probably wouldn't hestitate to use the Motul 300V if redline were not readily available. I use Castrol Syntec. Here it only comes in 5-50. The guys at Auto Europe told me to use it..

+1 for Castrol Syntec 5w50 (but not because I have to) FWIW, Redline is less susceptible to high temperature degradation than either of the Motul oils. HTHS for Redline, Motul 8100 and Motul 300 V are 4.6, 3.92, and 4.51 cp (all for 5W-40).

HTHS for Amsoil, Mobil 1 and Havoline are 4.2, 3.6, and 4.1.

I really like redline, but probably wouldn't hestitate to use the Motul 300V if redline were not readily available.
HTHS for Amsoil 5w-40 is listed as 3.7, while I couldn't find one listed for Mobil one. HTHS is a measure of kinematic viscosity, so there's no clear "higher is better" or "lower is better" rule regarding HTHS comparisons.

John HTHS for Amsoil 5w-40 is listed as 3.7, while I couldn't find one listed for Mobil one. HTHS is a measure of kinematic viscosity, so there's no clear "higher is better" or "lower is better" rule regarding HTHS comparisons.

John
It's a little more than just a measurement of kinematic viscosity. The High Temperature/High Shear (HTHS) Test is a standardized test (ASTM D-4683) and measures a lubricant's viscosity under severe high temperature and shear conditions. The test is intended to simulate the conditions found in an engine's crankshaft and connecting rod bearings, as well as other narrow regions. This measurement has important implications for such factors as engine fuel economy, valvetrain wear and bearing protection. The more resistant an oil is to high temperature viscosity loss, the better it protects, and even a small HTHS difference can make a significant difference. I'm surprised at the number of responses for Castrol Syntec. It's known to be a less than pure synthetic and yet a number of you are using it and actually seeking it out. That is not exactly correct...

Several year back, Mobil sued Castrol over the term Synthetic. Both are synthetic, Mobil used to make theirs in a test tube, Castrol started with regular oil and modified it. Both end up with "synthetic", just made differently.

In any case, from what I been able to determine, Castrol uses different combinations of base to manufacture their synthetic for different viscosities (just like Mobil), and most experts consider Castrol Syntec 5W40 to be "pure" synthetic (just like Mobil 1) - at least they used to until very recently. Recently, the packaging was changed and it's now manufactured in the US (instead of Europe) - nobody know if the formulation changed or not.

I do know that the Castrol Syntec 5W40 meets or exceeds all of the standards listed in the owner's manual for what our car needs. The Mobil 1 Diesel only meets the API rating. As to whether or not that really matters...

I also open to alternatives, but it must be readily available, 5W40, and good stuff. Unfortunately in the oil world, things can change very quickly, and what was the best may be re-formulated to just so-so. Or the other way around. I'm so confused... HTHS for Amsoil 5w-40 is listed as 3.7, while I couldn't find one listed for Mobil one. HTHS is a measure of kinematic viscosity, so there's no clear "higher is better" or "lower is better" rule regarding HTHS comparisons.

John
A quick search reveals Amsoil 5w-40 HTHS at 4.2

It's a little more than just a measurement of kinematic viscosity. The High Temperature/High Shear (HTHS) Test is a standardized test (ASTM D-4683) and measures a lubricant's viscosity under severe high temperature and shear conditions. The test is intended to simulate the conditions found in an engine's crankshaft and connecting rod bearings, as well as other narrow regions. This measurement has important implications for such factors as engine fuel economy, valvetrain wear and bearing protection. The more resistant an oil is to high temperature viscosity loss, the better it protects, and even a small HTHS difference can make a significant difference.
Good explanation - I was just pointing out that it was a viscosity-related measurement, and not some other high-temperature degradation metric like Noack volatility. From what I understand, HTHS is much like picking a motor oil weight at the start - lower numbers and you get better efficiency and higher horsepower, higher numbers and you get better wear protection, all other things being equal. So, it's a tradeoff, and not a case where the lowest or highest is necessarily best.

John There really is no way of determining which is best. I'd be surprised if there is any real world difference in any of the full synthetic oils as far as engine longevity is concerned.
So using what is readily available is fine in my book. I'd be surprised if our engines had oil related failures as long as we use sythetic and follow a drain interval no longer than recommended by the manufacturer. A quick search reveals Amsoil 5w-40 HTHS at 4.2


This page, on Amsoil's website, says 3.7:

http://www.amsoil.com/StoreFront/afl.aspx

Note apparently there was a reformulation on 12/05, according to the same page.

John I hear ya Tim and have read about the dispute between Castrol and Mobil 1

I say it's not a true synthetic because the base stock starts out life as dino fluid. Who knows what they do to it to modify it so they can call it synthetic, but I'm sure it's a good oil. This page, on Amsoil's website, says 3.7:

http://www.amsoil.com/StoreFront/afl.aspx

Note apparently there was a reformulation on 12/05, according to the same page.

John
interesting. other sites I pulled up list it at 4.2. the site you posted has an "updated as of 12/05" listed on their specs, so I'll go with that. You're right. I'm wrong. Good explanation - I was just pointing out that it was a viscosity-related measurement, and not some other high-temperature degradation metric like Noack volatility. From what I understand, HTHS is much like picking a motor oil weight at the start - lower numbers and you get better efficiency and higher horsepower, higher numbers and you get better wear protection, all other things being equal. So, it's a tradeoff, and not a case where the lowest or highest is necessarily best.

John
Point taken. I was referring to higher HTHS being superior with regards to protection. As with almost everything, there is a trade-off between performance and protection/reliability. I say it's not a true synthetic because the base stock starts out life as dino fluid. Who knows what they do to it to modify it so they can call it synthetic, but I'm sure it's a good oil. That's part of the problem with figuring out if Castrol is good or not. Apparently some of their oils are formulated from "pure" synthetic, and others start with dino fluid base stock. The 5W40 used to be one of the "pure" synthetics. Now it may or not be.

I would like it if Mobil made a 5W40 that was made expressly for gas engines. Although the diesel formulation is probably more than sufficient, I'm not sure that it wouldn't be even better if it didn't have all the stuff in it to meet the diesel requirements.

I'm still so confused... Just for my own education, doesn't the climate make a difference for what weight/viscosity to choose? I use Mobil one but would like to try the Delvac diesel product mentioned here in my MR2 Turbo. It is a naturally hot running motor. Also it is an older motor so I wonder if that makes a difference for the diesel engine oil. Thanks for any advice.

z Do another poll with all the choices
Done:


The only thing is, everyone has to vote again... They used to make one, I have a 5 liter jug of it sitting here.

I asked the lube engineer on another forum(Ducati) about the Mobil 1 'Diesel' he said it would work very well in the gasoline engine.

Mark


I would like it if Mobil made a 5W40 that was made expressly for gas engines. Although the diesel formulation is probably more than sufficient, I'm not sure that it wouldn't be even better if it didn't have all the stuff in it to meet the diesel requirements.

I'm still so confused...