Synthetic Oil vs. Conventional Oil

I had just bought a brand new car and decided that I would use my old 1987 toyota tercel, and a friends 1987 tercel in a real world head to head test. My tercel had 190,000 km and my friends tercel had 162,000 km both cars had always used conventional since new (10w30) both cars were automatics and both were driven all year round.

So we had 2 cars that were basically the same, with the same motors, the only real difference was the km’s between the two. We decided to fill the tercel with 190,000 km with fresh synthetic 10w30 oil and the tercel with 162, 000 km with fresh conventional 10w30 oil as this car should have more life left due to the lower km. We also filled both radiators with fresh coolant and checked to make all was working fine. 

In our first test we adjusted both throttles so both cars were reving at 4000 rpm in park. We left them this way from 10:30 am to 10:00 pm (11.5 hours) we then turned off the engines and looked at the oil in both cars. The synthetic oil looked and smelled fine, but the conventional oil looked burnt and smelled burnt.

In our second test we basically did the same thing as in our first test, but this time we let both cars rev at 4000 rpm for 3 hours every day for the next 3 days (gas tanks were filled before) We then again looked at both oils, the synthetic oil looked fine and smelled slighty burnt, but the conventional oil looked burnt and slightly sludgy (sludge was forming, meaning oil was completely broken down, will not provide good engine protection) This definitely shows use that the synthetic oil held up much better than the conventional oil under hars conditions. 

But wait! we still had one more test to do, and it will be our final one. We ran both cars just untill they hit normal operating temp, then turned off the engines and drained all the oil out of each car. We then started both engines without any oil in them and started our stop watch to see what would happen. The tercel that was running the conventional oil ran for 1 min 15 sec then seized completely. The tercel that was running the synthetic oil (by the way it was castrol syntec) ran for 3 min 23 sec then stumbled then seized. The synthetic oil actually stuck to engine parts which protected the engine far longer.

So there you have it, a real world test that proves synthetic oil protects much better than conventional oil. I will never run conventional oil in one of my vehicles ever again it provides very poor engine protection.