I have been using synthetic blends in my old Toyotas for a time and as my cars dripping oil a bit, been wondering if I should go full conventional. I see many debates on if I should use high mileage oil, but even more curious is just looking at Amazon there really are no actual 100% conventional oils to buy? There is an Amazon brand conventional, have used and sure it is fine but has anyone else noticed that about everything becoming synthetic blend?
They still exist, I got 5 quarts of the stuff at NAPA the other day
You can still get plain dinosaur oil from the big brands. Everything is moving towards synthetic but we are not there just yet.
The reason you are seeing leaks is because you have gaskets or something that need to be repaired. Switching to conventional will not solve your problem. It is a thicker oil, yes, but essentially you still have gaps/leaks you need to fix.
A lot of modern "Full Synthetic" and other synth-blend oils use Group III/III+ base stock, also known as "hydrocracked", "HC-synthetic" or "VHVI" oils. These are basically conventional oils that have been a little bit more refined. It's super cheap to produce and, thanks to old Castrol vs. Mobil lawsuit, can be called synthetic because it was "on par" with true synthetic oils of the time.
If you don't want to take the engine apart and change the seals, I'd recommend using a high-mileage oil or some synthetic oil with esthers in it. Esthers help the oil to stick to surfaces inside the engine and it has a nice side effect of filling the old and shrunken seals and rejuvenating them, stopping the leaks.
See this video for details.
