Is anyone using 20W-50 in their Cougars? I want to use Valvoline VR1 Racing oil because of the zinc and the local parts store only has it in 20W-50. I am old school I think and have always used 10W-40. Any comments?
If you are in Idaho, 20-50 will be fine in the summer. But it gets awfully cold there in the winter so you may have to go down to 10-40 or 10-30 if you drive that older car in the winter unless you store it then. With the other weights use a zinc additive and you’ll be fine if using a modern conventional oil.
Factory spec is 10w30.
Just ask them my local napa can overnite 10w30 VR1, they now carry both here in a town of 2500 in rural iowa. Order from summit too if the locals wont.
I’ll use 20-50 in a stock 1970 - 351W during the summer with no issues. Should be able to find non-synthetic Castrol GTX easy enough (or thru Summit Racing if the local auto part store doesn’t have it).
When it gets colder, I switch to 10-40 (regular or synthetic works fine). In either case, I would add Endelbrock Zinc additive if you have the original cam.
Use Mobil 1 15w-50
Walmart always has the best price. Check online before you go. Not stocked in all stores
AT-205 Reseal, Lucas Oil treatment, zinc additive, and of course STP high mileage!