That's great to hear. I'll never put Castrol GTX 20W-50 in mine again.

Should I dare ask why?

I have been using Castrol GTX 10-40 winter and 20-50 summer for years in both cars. I use either the Porsche oil filter or the Mahle-both have the correct oil valve to prevent draining of oil in filter when shut down. Keeps oil pressure up on critical startup. I change the oil at 3K or 4K intervals. I've had no problems.

NOW, Castrol has lowered the amount of Zinc-ZDDP to .12% from what I have found. Racers on the 911 board and others swear the Castrol GTX oil is crap and foams-under severe driving conditions. When it foams the rod bearings fail. BTW if your car has 100K to 125K mileage=replace the rod bearings anyway.

I will go with a Valvoline RO. Redline or do further research in the future.

GL
John_AZ

Interesting, should I just add a Zinc/Phosphate additive or run the engine for a bit and change the oil out to Valvoline Racing? The original oil was pretty bad, so worse case the Castrol will help flush the engine of gunk if I decide to change to the Valvoline.

Rod bearings- I guess I'm in denial that I need to change them being it's such a big job. I do have a bit of an oil pressure gauge bounce but the pressure is 2.2 bar hot idle, 4.5 running so I guess I have a bit of time. Besides I know my throughout bearing is on its way out meaning entire clutch job. I suppose I need to pick my battles!

So much to do so little time......

When you decide to change the oil you might consider using SeaFoam for a very short time/mileage before you change oil and then drain and change filter.

Now is also a good time to change the transaxle fluid if you have not done it. If the PO left you with nasty oil, he may never have changed the trans fluid. Many posts on preference and you will need 2 liters. Most often suggested, AmsOil, Swepco, Redline, Mobile1===whatever you choose must be GL4 specific.

GL
John_AZ

I will seafoam it at some point. I guess I was worried about getting leaks afterwords but I've read a bunch of people have done it with good results. I changed the transmission fluid with the motor oil, it was pretty skunky stuff!! I put in Valvoline Durablend synthetic blend, seems OK. Shifts much better. I'm sure there is higher quality stuff, but for now it's good.


By the way, it's been a full week of driving and no stumbling/stalling. Problem was definitely the DME for anyone else tearing their hair out over similar symptoms.