Was looking over my stocks to do an oil change this weekend. In looking at the oil on hand, I've somehow ended up with 2ea of the following 5 Quart/Litre containers of M1:
- 15w50 "Extended Performance" (Gold cap)
- 5w40 "Truck & SUV" (Silver cap).
I remember buying the 5w40, as there was no "European Car Formula" to be found at any store at the time. I drive three season only, so the 5w## part didn't worry me. But I have no idea how I got the 15w50, and no receipt to return it even if I did.
Soooo, is there any way to mix these (say 1 of each) and stay within Porsche specs/get best usage range, if I'm a three season user? Obviously, risking the engine isn't worth ~$50 of oil! However, if it is a simple 50:50 mix = 10w45, this would be within the owner manual's recommendation of up to 15w50 at "generally higher than 50 degF/10 degC", with more flexibility on the low end for some of the colder days in fall and better protection on the high end for a summer DE.