>>..I was using Valvoline Racing 20W/50, but switched to Mobil1 15W/50.
>What makes you choose one over another ? The thickest synthetic I've
>found is from Sellina (Fiat) who do a 20W/60 for racing that should hold
>prssure better. Anyone know about Motul ? I've been warned off thick
>mono-grades by others with vintage cars.
My car came with Dinosaur juice in it, and 20W/50 was recommended to
me. After reading some oil data, I settled on the Valvoline because it
had more ZDP (Zinc) in it. This compound is supposed to provide a
little extra protection in case of metal-to-metal contact. The 20W/50
made sense with a HUGE sump (7 quarts) on a TINY motor. I'm thinking of
adding an oil-water intercooler to warm the oil up quicker. Another
racer I know recommended a Ford part from the Thunderbird SC. It's
about $200, tho. The cheaper Marine grade units are just too big for my
installation.
The reason I switched away from petro to synthetic was film strength.
Note the caution about oil pump drive gears? I was chewing up drive
gears at a rate of one per race! I did 3 things to fix it, one of which
was going to Mobil1 for film strength. It was a definite oil related
failure. I even rigged an external oil line with a metering orifice to
spray the drive gear, to no avail. I did re-align the pump internals to
reduce friction, but the bottom line is that the drive gear is doing
twice the amount of work as stock. The gear on the cam was fine, as it
was hardened along with the cam. The poor driven gear was being eaten
alive. It's a steel gear too, not plastic or brass. It's ok now.
Thanks for the pointer to Phoenix. There's another outfit in England I
should call. I can't remember the name, but I have one of their ads.
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