ORIGINAL: w8ye
It is a well established fact that if you mix synthetics at heavier ratios than recomended - you will get hard carbon formation
Not disputing the fact that these oils can produce hard carbon, just stating what is listed on the bottle. Seems just wrong that reading instructions can get you into trouble! Thats why I don't use brand X 100:1 oil!
I can wipe the carbon off the tops of my pistons with a rag ..... Pennzoil user at 40:1. Just did that with my 5 year old DA-50.