Originally Posted By: afoulk
My brother called me tonight wanting to know what oil to use in his GTI. Its one of the newer ones with the 2.0 turbocharged 4 banger. He couldn't remember what they call for and he had the dealer do it the past couple times. He daily drives it in the fair weather months and does mostly car shows with it, but once in awhile he'll take it downt he 1/4 mile. Its chipped with an intake and turbo back exhaust. Anyways, I told him I figure it calls for a 5w-40. And I said i'm not up to date on VW specs, but if it were mine, I'd go with either GC, Rotella T syn., or Mobil 1 Turbo Diesel Truck. I think hes more than likely gonna go with the GC, but I wanted to double check with you guys.
Any of those three are pretty good choices. The Rotella sounds interesting to me because of it's strong performance in subi turbos. The Mobil 1 Turbo Diesel Truck sounds interesting because of its higher HTHS and more ZDDP than Mobil 1 0W40. We don't have any used oil analysis on either of those oils yet on this engine that I know of. GC has shown some of the lowest shear rates in the database. We have over 40 used oil analysis on this engine and we know what it does to oils (beats the heck out of them in short order). This engine poses a unique challenge for oil due to the following factors:
1) Turbo Because this engine shears down even the best oils in a very short time, I would look at real world performance in used oil analysis first to see how much oils sheared and High Temperature High Shear (HTHS) performance second. Even the most shear stable oils are shearing in this engine.
VW 502 requires a HTHS of only 3.5 cP. I personally would use an oil with a higher HTHS viscosity than oils which are made to be just above the 502 minimum.
2) Fuel dilution This DI engine is a notorious fuel diluter. All oils have seen lowered flashpoint and thinning in this engine, it is only a question of how much.
3) Flat tappet type fuel pump follower and cam I would not use an oil with low amounts of ZDDP in this engine. Many recommend 1200ppm as a minimum for flat tappet engines and that may be a good rule of thumb for this engine (in the absence of more exotic additive packs that is). Typically a dealer may use syntec 5W40 which is fairly low in ZDDP as seen in this VOA:
Calcium 1053
Magnesium 926
Phosphorus 786
Zinc 918
SUS @ 210 70.7
Flashpoint 400 F
TBN 10.8
4) Deposits on intake valves, etc. from pcv system If he hasn't already taken measures to address this problem he should do so immediately IMO as this outweighs by far the choice of oil. Oil related factors related to this issue are cleaning ability and volatility. the problem is not due to the oil, however, it is a DI/design issue. Oil choice can only help slow down the deposit formation.
FWIW, I have been using redline 5W40 and the results have been good so far. It has shown some of the lowest shear rates, higher flashpoint retention, and lowest iron levels in the database. There doesn't appear to be a single magic oil for this engine IMO, only "different grades of destruction" ha ha. The fe numbers are shown in the graph below with some of the better than average "wear" used oil analysis identified (outliers of carradio's failing follower, adeere's 99% highway runs, and agpatels "who knows why there is so much iron with all oils on that engine" have been removed. Also many of these can be considered "single pass" used oil analysis and the data is on multiple units so take it with about a 55 gallon drum of salt). Also the Syntec 5W40 used oil analysis are shown in yellow just becasue that is an oil I was studying when I made this graph