Slippery Deal

Rick, you are always telling
us you use Mobil 15W50
synthetic oil. I have several gallons
of 5W40 Mobil synthetic.
I have run it in my 1987 Goldwing
motorcycle for several
years. OK to use it in place of
your recommendation for the
musclecars such as my ’70 440
GTX? I got 20 jugs for a $1.00/
gallon when the heavy truck
dealership I worked for closed.
R.I.P. Sterling Trucks.

I wouldn’t use it straight. While it has
enough ZDDP, the cold viscosity is on the
thin side, especially in your climate. A
50-50 blend of the 5W40 diesel oil and the
15W50 should be fine, however, allowing
you to use up your “score”.