Originally Posted By: bluesubie
Originally Posted By: fredrik94087
odd that I can't find this thread using the forum's search engine, but managed to find it using google search.
I have a 2015 wrx.
2500 to 8,000 used RP 5w30.
8,000 to 17,500 used RL 10w40.
17,500 to 21,500 (present) Mobil1 15w50
2500 mile OCI. No oil loss that I can measure.
I am running an oil cooler. road temps get to 205F. Track temps get to 230'ish.
Car is modified.
I dont drive until temp hits 90F and never push hard until 180F.
Do any of the old timers here see any issue with running mobil1 15w50 instead of Redline 10w40 as far as wear protection.
I am mostly concerned about rod bearings as they would be the first to fail.
The HTHS viscosity of RL 10W40 is 4.4 and HTHS of M1 15W50 is 4.5. Probably not too much difference in bearing protection. I presume you have bearing clearances that call for a thick 40 grade or 50 grade.
RL is thinner at operating temp and is loaded with moly so theoretically it should rev more freely. And Red Line's POE base stocks are cool.
Subaru calls for 5w30 A3/B4 oil. There is no way I am running that thin of an oil and risking bearing failure.
I am running thicker oil because my installer who has built these motors told me there is plenty of room in the OE motor for thicker oil. His recommendation was to run the thicker oil as cheap insurance.
I am probably the only guy with an FA20DIT running 15w50 and an oil cooler. I do like Redline, but Mobil1 is about 1/2 the price at 2500 OCI.
My concern with the Mobil1 is that it is an A3/B3 while Redline is an A3/B4 (recommended).
Thanks for the input. I only looked at the ZDDP content of Mobil1. So, the higher Moly amount in Redline will reduce friction over Mobil1? Ok.
Mobil1 15w50 from another site:
zinc = 1,133 ppm
phos = 1,168 ppm
moly = 83 ppm
Redline 10w40 from this site:
Zinc: 1446
Phos: 1337
Moly: 677
I believe the phos is higher in Mobil1 than what I copied, but I suppose I have talked myself through it with your help.
Never looked at the Moly content. I was looking at viscosity and ZDDP.