Interesting observations (M1 0w40 vs GC 0w30)

[crew219]

I have a fuel diluting Audi 2.0t FSI.

Have been running mostly GC 0w30, but this past oil change I put in M1 0w40 due to availability. Previous OCIs on the GC were in the 4k mi range. 2k miles into this oil change with 0w40 M1, I pulled the dipstick to check consumption and noticed that the oil still looked very clean. In fact, the oil blot on the white paper towel was mostly amber. GC always turns dark brown within a few hundred miles, and is mostly black within 1k. Now I realize that the color shift can be attributed to additives in the oil, but the oil itself just seems cleaner.

The second observation I've made is that my car pulls more vacuum with M1 0w40 vs GC 0w30. Normally the engine @ idle is around 19 in/hg with GC, but now it is a consistent 20 in/hg with M1. Upon engine braking, the vacuum shoots up to 22in/hg with M1, and normally only 20in/hg with GC. The changes in vacuum have also been noted with 5w40 castrol syntec (dealer oil).

Any thoughts or comments on these two observations?

I'm going to pull a UOA on this M1 @ 4k and see if I will end up using this oil in the long run.

Dave

 

[Steve S]

the 0w/40 M1 is a great oil .

 

[Quattro Pete]

Originally Posted By: crew219
Have been running mostly GC 0w30, but this past oil change I put in M1 0w40 due to availability. Previous OCIs on the GC were in the 4k mi range. 2k miles into this oil change with 0w40 M1, I pulled the dipstick to check consumption and noticed that the oil still looked very clean. In fact, the oil blot on the white paper towel was mostly amber. GC always turns dark brown within a few hundred miles, and is mostly black within 1k. Now I realize that the color shift can be attributed to additives in the oil, but the oil itself just seems cleaner.

Some people would claim that GC turns darker because it's doing more cleaning. But I don't think anyone can call it a fact.

From my personal observations with M1 0w-40 and GC 0w-30 in a 1.8T engine, I had a feeling that the engine ran smoother on GC, but also wasn't as rev-happy and caused slight degradation in fuel economy. But I haven't done any scientific studies to confirm that. However, GC did deliver slightly better UOA results in my case.

Is the difference betw. 19 and 20 in/hg a significant one or is it within a margin of error?

 

[OilGuy]

Additives can turn dark after being exposed to engine temps. Color of oil is almost meaningless - the human eye is a very poor oil analysis machine.