Originally Posted By: A_Harman
Originally Posted By: Garak
I'm assuming you're talking about the 0w-10 racing oil. I wouldn't do it. ZDDP levels are at 2400 ppm, and that's corrosive. I would also suspect it has little in the way of detergent, and the Red Line site recommends changing it more frequently than regular motor oils. At $13 a quart, that could get costly.
Also, I'm sure, being Red Line, it's got a higher HTHS than its 0w-10 designation would indicate.
Been there, done that.
Years ago I've used RL 0W-10 to try and thin out some 20wt oil and it didn't work.
It really isn't that light an oil and right on the bottle it states that it has a higher "bearing viscosity than most petroleum 20 Wts". That means a HTHSV likely just over 2.6cP. It also has a VI of only 130 so this oil will be heavier than all 5W-20 dinos.
The ultra high VI OEM 0W-20s like Mazda USA and Toyota will be much lighter than RL 10wt anda ll temp's and even RL 5wt race oils on start-up.
The lightest oil currently available is the Sustina 0W-20 due to it's 229 VI. In fact it's quite a bit lighter than the already very light Toyota 0W-20. My oil pressure at 80C was more than 10% lower with Sustina vs Toyota which really surprised me and lower than I wanted. I added a pint of Sustina 0w50 (est HTHSV 3.85cP, 178 VI) which more than made up the difference.
Garak is on top of this one. I wouldn't recommend running their 10WT racing oil undiluted for daily driver use for the reasons he states.
But maybe we could consider blending the 10WT with street oils to see if we can get a "normal" street oil with HTHS below 2.6. Redline doesn't publish the HTHS of their racing oils, but doing a Viscosity Index calculation, and converting to dynamic viscosity, I estimate that their 10WT oil has an HTHS of 2.0cP, which is actually the same HTHS that SAE is considering for their proposed 0w10 grade. If you were to do a blend of 50% 10WT racing oil with their 0w20 street oil, you would end up with the following viscosity characteristics:
KV40 = 34.1, KV100 = 6.5, VI = 148, and an estimated HTHS of 2.3. This is the min HTHS that SAE is targeting for their proposed 0w15 (or is it 16?) grade. This mixture would still have zddp far in excess of what modern street engines require, and would still be a short-drain oil, but the viscosity would be a significant step down from normal 20-weights. Maybe you could detect a fuel economy difference. But the cost savings would be eaten up by the use of an expensive short-drain oil.
