Engine oil

[cally]

What brand engin oil do u guys use?? and is it 10W-50?? i now has changed to a brand name G Plus Respo, and i used this brand for a long time on my subaru. this engine oil makes the car smoother and more quiet and even when standing still the car wont shiver a single bit. and also when driving, the car wont wanting to stop, when u are driving its just keeps on sliding and sliding without stepping on the gas. until u put the brakes on. So i decided to use it on my RS4 in 1500 KM oild change. they chosen 10W-50 for my car and after changing it has all the things i mension, but dont know why the power in 2000-3500 RPM has weaken, i dont dare to try the high revs yet. i choose this brand to use because last time my subaru had a very very big difference after using this oil it makes it rev up smoother and quicker but i havnt try the low revs so dont know is it this engine oil is too fine "the texture" so that it will react in this way.

[Audihead]

I run Castrol 5-40 Synthetic when the dealer does the change. But, when I go to my independant mechanic I use ELF Excellium 5-40 Synthetic. I feel that you using 10-50 is a bit to thick for the RS.

[cally]

mmmm the texture is to thick?? what actually is the reaction that thicker and thinn will give??? very complicated...

[Steven Shiu]

i use motul 300v 5w/40 and is quite good

[RI_RS4]

i use motul 300v 5w/40 and is quite good

Steven, how do you know that Motul 300V 5W/40 is "quite good" in your RS4? Have you done oil analysis to determine this, or is this an opinon based on prior experience, the excessive cost of the oil, or marketing hype?

I have over 40 oil analysis records on 13 RS4s, including an analysis of an engine running 300V. Every analysis sample of Audi 502 approved oil shows high fuel dilution (fuel getting into the oil) and abnormally high iron wear. A friends car with 300V not only had high dilution and high iron wear, but also had high tin, which is a very bad thing, since there is very little tin in our engines.

The reality is that there are no "good" Audi approved oils in the US. In Europe, Fuchs Titan GT 5W-30 is the factory fill. It's not bad, but it still has relatively high wear. The best commercially available oil that we've seen so far is Amsoil European Formula 5W-40. This, however, is not an "approved" oil, yet it is significantly better than all the others we've seen, including Mobil 1 0W-40, Motul 300V 5W-40, Motul 8100 Etech 0W-40, Motul Xcess 5W-40, Castrol Syntec 5W-40, and Elf Excellium LDX 5W-40. If you use any of these oils, they should be changed out every 3000-3500 miles, at which time they have been significantly degraded.

The best oil in this engine is a custom blend that I had Terry Dyson, an expert in oil analysis, develop in conjunction with a small companie called Renewable Lubricants. The oil is a Bio Synthetic blend that has incredble properties, and quite literally blows away all other oils, with 1/3 the wear and at least 2x the life.

[RI_RS4]

mmmm the texture is to thick?? what actually is the reaction that thicker and thinn will give??? very complicated...

Cally, increased viscosity (thickness) causes increased resistance to flow. If the viscosity is too high, oil will not flow to the bearings quick enough during cold start to lubricate the motor. (Similar to the difference between pumping water or maple syrup through a hose.) Audi's are designed to use and oil that is 30W to 40W when at operating temperatures, and 0W to 5W at cold. Other ranges can be used if you know what you're doing, but to be safe, you would want to have a before (old 5W-40 oil) and after( new whatever) oil analysis done, to be sure that you did not increase bearing wear beyond what is normal.

[RI_RS4]

Cally

G Plus Respo is a taiwanese oil, I believe. This engine is not designed to run a 10W-50 oil. If you live outside of the US, then I'd try to find Fuchs Titan GT 5W-30, which is probably the best Audi 504 approved oil. If you live in the US or Canada, then get yourself some Amsoil 5W-40. It has proven to be the best commercially available oil.

If you want the best oil you can get for your engine, then you can contact me for information on the custom oil I had formulated. If you agree to have oil analysis done on your engine, and share the results for our study, I will give you the information on where to have the analysis done, and where to purchase the oil. (BTW, I have no financial interest in the oil whatsoever. Just a love for the RS4 and keeping the engine together for a very long time.)

[cally]

RI RS4,

I live in Hong Kong, so dont know if i could purchase the oil brands that u mension above, but i will try to find it. i thought the oil that i am using 10W 50 is to thin... cos its just kept on sliding and sliding very smooth feels like never wanting to stop and its a big difference then stock oil feeling... and before reading these replies i was thinking of using a thicker oil... maybe i should try thinner first. but really it feels like the
its thinner then the stock oil.