I have a 2003 Toyota Camry 4-cylinder conventional engine with 170K. Car has run like a dream with little or no work. Changed the plugs at 150K. Cleaned the throttle body and MAF about 15K ago to solve a rough idle problem. Still original brakes....In other words, little, if any troubles. But, in the past couple of years, it uses a quart of oil about every 3 to 3.5K. I have been using High Mileage oil for the past couple of years and that seems to slow it down a bit, but not stop it. Anyway, due for oil and filter change. For some reason, my local go-to auto stores only have Hi-Mile oil in Synthetic or SynBlend. I suppose I could go on a hunt, but really not in the mood. And no, I did not ask anyone at any of the stores. So, my rig has lived its entire life on dino. I hate to mess with success, but if I do == GULP == switch to SynBlend this time, it should be O.K., should it not?
At that mileage stick with Dino, but up the viscosity for "better" protection. Will not stop oil burn, but will likely stabilize or reduce the "rate of increase".
I'd think as long as it's high mileage oil that's all that matters. You just don't want to go back to regular oil, synth or regular: the high mileage oil swells valve guides, and switching back to regular they will contract, worse than they were to begin with.
I don't want no blood on my hands (getting blamed for a change gone bad) ...but you can check for example the Mobil 1 web page they discuss this situation I believe.
Good reason to stick with high mileage. Those oils are also on the thick end of the label weight. Going thicker won't hurt, and will slow the burn rate, but will also lower the fuel economy. Perhaps not enough to stand out, but the engine will work harder to pump it. Synthetic blends are maybe 30% 'synthetic'. They won't harm the engine, but the concern is more with them being better at cleaning out the passages. So people worry about them cleaning out gunk that has been plugging a leak. Since it sounds like your oil use from more getting past the cylinders from the wear after all those miles, I don't see a synthetic making that worse by cleaning the system. Plus, you are using the high mileage oil which already swells the gaskets.
Not all oils play well with each other due to composition and additives. You stated using dino up to this point, now considering switching to blend or full synthetic for reasons stated. When ever one does this, best practice is to do an "early" oil/filter change after switching (say 500 miles) to flush it.
Oil filters actually clog up quickly, even with sticking to the same oil brand. Their bypass valve is probably open for longer than it is closed during the oil change interval. I once changed the filter halfway through, and the opaque oil became almost out of the bottle clear after a week of driving. The people that design engines and oil formulations are likely aware of this. So I don't worry about it.
