Originally Posted By: sunfire
Won't switching brands sometimes cause a little extra engine wear? That's why people recommend doing 2 OCIs before doing a UOA. Some say its because of the different additives in the new oil and some of the old oil still in the engine.
But if the additives clashed I think we would see some more stuff in the UOA.
I really feel that as long as you change the oil with another normal oil (ie API-SL/SM rated and approved) that its really not going to matter.
Now as far as a UOA, it would be better after the 2nd OCI then to run a one as most of the oil in the engine is going to be the same. And then the UOA will reflect what/how the engine/oil is doing OCI after OCI.
Also, if you are going to stick to a certain brand and like how it performs then do a UOA BOTH in the Summer and dead of Winter.
With a little trending you'll have a excellent idea how things are looking.
Of course, I've had hundreds of thousands and over 25 years of never running a UOA and my engines never has issues.
I guess I was "lucky" when I ran my first one and it came up with a coolant leak...
Lucky me..
But it DID prevent major damage if we allowed the leak to continue on.
Really changing brands is not a problem unless you are selling a brand of oil, then it is a problem.
Bill