So, i've been using the search and all, but i kinda had my own little question about synthetic oil, and ive seen different answers....My car has 199k miles on it, and im thinking about switching to royal purple synthetic... my couple of questions are

1. Should i switch with this many miles? Some threads are saying that switching with this many miles could cause leaks? I think someone said something like "On a motor with high mileage sludge is one of the things keeping it together"
2. Will i notice any better gas mileage with synthetic vs conventional?
3. Is it even worth changing over? I'm not trying to kill my motor because of an oil change.

 

I was wondering about this too. My car is only at 80,000 and I was debating on switching to Royal Purple as well. But upon talking to the Associate at the counter of O’rileys they were suggesting just to use oil that advertises High Mileage, rather than the full synthetic. So if my car is at 80K and that is the suggestion I would just stick to the High mileage oil for your car.

 

Make the switch. The oil itself won't cause any problems, but there is always an issue with weakest links. Royal purple is junk, use Amsoil. I change my oil once every 2 years, the stuff pays for itself.

 

The problem with switching to synthetic after so many miles on a car is that it will cause leaks.

Not because it's breaking anything, but because the full syn oil is so slippery that it an fit through smaller cracks and even slip through gunk that may be preventing some of the leaks that would otherwise be there if it weren't for the gunk plugging it.

 

I've made this switch on 3 cars. First was a 2000 Honda CRV(~120K), Next a 2002 Sport Trac(~75k miles), and lastly the 98 Vert ( either 85k per odometer or unknown per title).

None have shown any leaking. The only thing I did notice was how dark the oil was after the first drain of the Synthetic, compared to what came out to make the swap.

Guessing Mobil 1 has a pretty high detergent level so it does a bit of cleaning.

And yes that's what I use Mobil 1.

Running Rotella in the Duramax, and for now the Miata I just got. Rotella is definently a high detergent oil and I want to make sure the Miata engine is cleaned out well.