GC Flashpoint & Turbo

[crew219]

Been noticing in UOAs that the flashpoint GC often drops down to 380F-340F after about 5k. IIRC the flashpoint of GC when new is 440F+.

Perhaps this isn't important when the engine is running, but I'm a bit concerned when the engine is shut off after normal or hard driving.

The engine does have an afterrun coolant pump which reverses coolant flow through the turbo after shut-off and pumps coolant from the radiator into the turbo in order to help prevent coking & deposits from forming on the shaft.

The car in question is a 2006 Audi A3 with the 2.0t engine. The turbo also sees hotter temps than normal due to performance modifications. The oil capacity is approximately 5 quarts (w/ filter). The vehicle is also driven 80-90% city & the rest is high speed, high RPM driving. All aggressive driving is done only after the oil has completely warmed up to temperature and cool-down driving is done before shutting off the engine.

I am currently running GC + appropiate dosages of LC & FP in the fuel tank. However, I am running out of LC and am considering dropping it completely in favor of a shorter OCI.

Given those conditions, would it be advantageous to cut my OCI in half and run the GC for only 2500mi? Right now I'm about 3000 miles into my OCI and am considering sampling it and doing a UOA.

Dave

 

[Quattro Pete]

If it drops to 340F, then the engine most likely has fuel dillution issues which should be addressed before doing anything else.

FYI, here are my results on gold GC after 5K miles in a 1.8TQ (modified as well), and it only has a 3.7qt capacity. No LC or FP either. I think you have nothing to worry about with 5K OCI in your engine, assuming you have no fuel dillution issues.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=002283

 

[Primus]

FF of 355-380F can be seen at GC quite often even if the fuel is below 0.5 %. Agree that it's quite low for a synthetic oil considered nearly as a bench-mark here ! I have tried to rise this issue several times, but people was so excited by the process itself that fully ignored any discussion on possible dark sides of the product.

 

[crew219]

quote:

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Originally posted by Quattro Pete:
If it drops to 340F, then the engine most likely has fuel dillution issues which should be addressed before doing anything else.

FYI, here are my results on gold GC after 5K miles in a 1.8TQ (modified as well), and it only has a 3.7qt capacity. No LC or FP either. I think you have nothing to worry about with 5K OCI in your engine, assuming you have no fuel dillution issues.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=002283

---

Indeed I am a bit worried about fuel dilution. The 2.0t is direct injection, 10.3:1 compression + turbocharged (21psi spikes, 17-18psi holds) + high RPM (4-7krpm driving). Seems like a candidate for some blow-by.

The driving habits will probably not change . . . just trying to gauge what would be the best OCI & oil for my driving habits.

Dave

 

[Doc Mike]

Hi Dave,
I've kept bookmarks of every UOA on the Audi 1.8t motor and some of them show very high quality oils like Motul, M1, Redline, and GC showing TBN of 2 or less by 7K miles and as you say, lowered flashpoints. I'd run no longer than 5K miles in a chipped 5 quart sump 2.0T. I am going to now be changing out after each race event as well. cheers! Mike

 

[crew219]

quote:

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Originally posted by Doc Mike:
Hi Dave,
I've kept bookmarks of every UOA on the Audi 1.8t motor and some of them show very high quality oils like Motul, M1, Redline, and GC showing TBN of 2 or less by 7K miles and as you say, lowered flashpoints. I'd run no longer than 5K miles in a chipped 5 quart sump 2.0T. I am going to now be changing out after each race event as well. cheers! Mike

---

Yeah I looked at the links I sent you and was pretty surprised at the flashpoints. The only UOAs that looked really good were Mike Pancheri's, but he didn't list flashpoints for those. In the big picture, oil is pretty cheap and not worth worrying about IMO.

BTW, nice turbo . . . I can only imagine how well your car pulls now.

Dave

 

[AndyH]

Dave,

I too have noted a lowered flashpoint (385°F) on my 5,810 run of GC in my 2005 Subaru Impreza WRX STi (with a Cobb Tuning Stage 1 ECU reflash). Here's the link to my UOA:
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic&f=3&t=003237

Personally I think you'll be fine with 5k OCI's in your A3, but your best-bet would probably be to run it out to 5k and have a UOA performed to see how the oil is doing in your A3.

 

[BlueWorld]

You've probably noticed how long it takes the engine to warm up in the 2.0T. The good thing about that is it means your cool down runs are very effective, so if your not turning off right after a hot run, I doubt you'll have to worry about the FP.

You could step up to a racing oil like Motul 300V Competition that's meant for high fuel dilution, but it's probably more cost effective to just do low OCI's with GC. I'm betting 5K OCI's are fine, but love like to see what your 3K UOA looks like.

Out of curiosity, how did you break-in your engine?

 

[crew219]

quote:

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Originally posted by BlueWorld:
You've probably noticed how long it takes the engine to warm up in the 2.0T. The good thing about that is it means your cool down runs are very effective, so if your not turning off right after a hot run, I doubt you'll have to worry about the FP.

You could step up to a racing oil like Motul 300V Competition that's meant for high fuel dilution, but it's probably more cost effective to just do low OCI's with GC. I'm betting 5K OCI's are fine, but love like to see what your 3K UOA looks like.

Out of curiosity, how did you break-in your engine?

---

Drove it gently up until 1k. Never hit higher than 5krpms . . . changed the oil at around 1250-1500mi (forgot now) with GC + new filter. Dealer changed again @ 5k with M1 0w40 and new filter. Never had more than a 1/2 quart consumption per 5k. Changed on my own with new filter & GC @ 10k . . . at 13k right now with no noticable consumption.

Just waiting for my oil sample kit to arrive from blackstone and I'll drain a bit of the oil for analysis.

Dave

 

[Volvohead]

Interesting thread.

If you look in the recent UOAs, there is a Volvo R owner who seems to have likewise noted relatively low FPs running GC.

The R is a relatively potent HO turbo engine, so there may be a turbo/GC flashpoint issue. I can't think it's a dilution problem in every instance.

FWIW, I'm planning to run RL in my R in the summer, and save the GC for the colder winter temps. I'm not sure how that chemistry change will play out, and so far no one has proffered any genuinely constructive thoughts on the matter.

 

[e36'n]

I'm running GC on my 92 325is Turbo and haven't gotten a UOA yet but will post when I do. Most of the fellow turbo BMW owners didn't agree on the use of GC in their setups.

With that said, does the decreased flashpoint have an effect on the oil properties?