Strange, most people refrain from using M1 due to it's inferior quality and premature breakdown in our Subaru engines. M1 was the worst offender of all the oils I've ever used in all 3 of my Subarus in the combined 250k that I've driven them.

 

(this is hearsay) apparently M1 products vary depending upon where they are purchased, as in the types sold in places such as WalQaeda (aka walmart) are of inferior quality compared to the types sold in traditional car parts stores

(based on other's purported data) Royal Purple is not a high quality motor oil, based upon lab tests and engine rebuild results.

I will be doing a Blackstone comparison between Redline, Amsoil, and the Subaru full-synthetic oils for my own edification. I'm currently on Redline now.

 

Mobil changed the formulation of Mobil1 synthetic not too long ago. It is actually a mineral oil blended with synthetic additives to achieve the synthetic labeling in the US, however it should meet all the same requirements to do so as well. I never had issues with M1 in my previous NA cars (multiple cars with over 100K), but with the turbo, it doesn't seem to do as well.

 

The old M1 worked well in my RS, but as soon as they switched the formula I started burning an insane amount of oil.

 

I didn't notice it so much in my other cars, but I definitely do in the turbo. I found this out when I had my 90K done. They used the Subie synth oil since they did all the fluids, and I noticed that it seemed to hold up better than the M1. On the next change I used the rest of the case of M1 I had and found that it was back to the same burning off, so this was a good indicator to me that it was the oil. Not a definitive test, but enough to get me to change.

 

Friend just sent me a link to a coupon, thought i share...

http://static.pepboys.com/images/cou...lfilter_cp.pdf

 

http://***************/?sdtid=389308...lfilter_cp.pdf

$35

 

+1 Rotella T6.

Mobil1 burned like an SOB in both my M3 and my Integra, so I only really use it when there is nothing better and I need oil.