You don't need to use M1 for all 3 flushes. I'd say just the last one. It's throw away oil, and that's a lot to throw away! And since you're putting it in only for a few minutes with a detergent/cleanser each time, it's not making any difference that you're using synthetic...you're cleaning it out and not letting it penetrate.

I vote dino oil the first two, then M1 the last flush and final fill. That last flush will be plenty for the M1 molecules to work their way in. Also, having 98% M1 and 2% dino won't hurt anything. You'll still get the slippery benefits of the M1.

If the truck has a ton of miles on it, be aware it may use a little oil after those 3 flushes. Sometimes a little gunk is a good thing if the seals/rings are worn. But carbon deposits are never good! And you may end up needing lifters (are they hydraulic or no?!) anyway, so be prepared!

Good luck! <img src="/forums/images/graemlins/kewl.gif" alt="" />