Would it be safe to switch from a regular oil in a '75 360 V8 to a synthetic? I read that you have to flush the system. Do you have to just drain it or is there more to the process? And is it worth it to go to synthetic?
No issues, just drain and refill. I've converted on several cars, no issues.
Only you can say if you need to. Synthetics can go further between oil changes, or protect better under severe conditions (especially cold starts in arctic climates). My last car, I converted at 130K miles and a cold ticking completely stopped. It went 308K miles on the original engine before the body rusted out. I saved the engine for a spare.
I have been using synthetic since 1988. Started with Neo. Been a Amsoil dealer since 1990. Which is better? After all this I do not know. I think gear shock on the dino is better. Cold weather is better with syn. With dino you can go say from 5/30 to 10/30 to help. With syn you can not unless you go with the cheaper syn an then you have to change it sooner. But in 100% syn by volume in too soon when new can be a problem no matter who says you can. Wait till you have 5,000 to switch. I put Reline in right away new and my valves did not seat Yes after 80,000 I would flush the motor with Amsoil flush. Sooner is a waste of time and money unless you go 10,000 to a oil change. I would not switch at all over 150,000. Do more harm than good.I have put over 300,000 on both in different cars. No difference that I can tell except the Amsoil did not seem to have as much as a power loss but that could just be the different engine. So to solve the problem go with a blend. Vavoline 100% syn is a good blend. That why Corvettes have it new. It has about 20% syn as far as I know (which is not much). Remember 1% syn is still 100% syn. US Gov. says you have to have 15% syn to call it 100% syn. Redline and Amsoil are true 100% by volume. Also remember racers tear their engines down as sop. They do not run like we do. So there is no longitivity there and forget about the advertising. Me, I am going back to dino because if you start burning oil it is way too expensive. It is anyway. You have to be nuts to go 25,000 on a oil change. I do use Amsoil oil filters. You can not beat them. I see no problem going 4- 5000 with good dino with a Amsoil filter. I change filter at 6000 with the top of the line Amsoil and Amsoil oil at 12,000. I guess I just feel better changing oil every 4000 on dino and 12,000 with syn. The cost is not much at each oil change with dino. Change Amsoil and it is a big hit all at one time if using series 2000. My Cad takes 8 qts. Ouch!Take it in and not change it yourself, you better trust who does it. They just might switch it and keep the Amsoil. So I did not go which is better here, just made some points.