Finding answers here is usually easy.I added some Castrol Syntec 5/50 to my Castrol Syntec 10/30 to top it off. I noticed the oil pressure at idle went from about 25 lbs. to 28.The next oil change using the same oil I added a half pint of Schaeffer Moly E.P. oil Treatment. The same thing happened the oil pressure at idle increased.Now I read that after about 4000 mi. on Chevron Supream 10/30 oil the oil sheered to almost a 20 wt.So if you were to add either of these Synthetic heavy weights say 1000 miles eailer would the Viscosity have held up to a 30wt or wouldn't it have made a difference.I may be off and even way off but I will learn something anyway.
OK so much for understanding Sheer and if it can be controlled.Then is this a true staement ( you never know from what you read).The lower the flash point the greater tendency for the oil to suffer vaporization loss at high temperatures and to burn off on hot cylinder walls and pistons.
The flash point can be an indicator of the quality of the base stock used. The higher the flash point the better. 400 degrees F is the absolute MINIMUM to prevent possible high consumption. So like oil sheer if your flashpoint goes down so does your protection.
