Originally Posted By: BerndV
Bill, I know you are a big dino advocate. However, my 96 Camry has had nothing but M1 starting at 5k until my very recent switch to Amsoil SSO. My intervals were 7500 miles under warranty and have been around 10k since. I had my valvetrain cover of at 149k to replace the PCV valve and the top end looked nothing like the pictures on this thread. It was, in fact, absolutely immaculate. If the top end on that Camry looks the way it does versus the Saab, I can only imagine what the bottom end must look like. Sure, the car will continue to run a while longer. It is, after all, a Toyota. That doesn't mean it wouldn't last longer and stay healthier with a steady diet of synthetic. Synthetics are particularly well suited to sludgers like these older Toyota engines.
That's the difference I saw with my 2000 I4 Accord fed M1 5w30 for most of its life and 7500mi OCIs. When I pulled the valve cover at 102k mi there was absolutely nothing stuck anywhere. Some dirty oil in some of the vertical holes that don't drain but absolutely no varnish or sludge.
Again, I'm not sure it matters though as long as the sludge doesn't interfere with the flow of oil or moving parts. My personal preference is syn but I've got nothing against dino in most engines. The OM is right about his savings adding up over the long term though done correctly (longer OCIs) and considering that the cost delta is ~$10 per change, the syn might perform better and cost the same or even save a few bucks.