Originally Posted By: GM4LIFE
Originally Posted By: 3800Series
Originally Posted By: GM4LIFE
I agree. Why 10W30? Why not run 0W30 Amsoil signature series? That's their best oil.
If money was no object I would run Amsoil 0W30 with an Amsoil EA oil filter and change it every 5K miles. I agree with 3800Series in that I would rather have fresh oil and a fresh filter more often than running the same oil and oil filter for a long period of time and a ton of miles.
I don't care what oils and filters guarantee in terms of protection, I would NEVER run any oil or filter for a long period of time. Oil and filters are cheap insurance and they ensure that you won't have an oil related failure. $30-$50 for oil and filter will protect thousands of dollars worth of engine repairs or engine replacement.
5k is on the very safe side. Not trying to bash anyone but synthetic oil (as a whole) has virtually no breakdown (over a reasonable time period).
Additives will be lost before the oil is actually bad. Oil is a 2 step system. Oil to lubricate additives to help better lubricate. Iv personally witnessed a women go 20k miles on conventional oil. And the car still runs many years later.
Would I do it? No, but my car calls for 7.5k OCI with conventional oil and this was rated back on oil quality nearly 20 years ago. I feel 10k is safe for a synthetic oil as long as you don't do 10 mile trips in your car and its all city driving.
Personally I follow the 7.5k OCI and I don't have a problem but I also drive 95% at speeds of 45-75. I'm sure if I wanted to push it I could safely do 12k.
I wouldn't change amsoil oil (or any other synthetic) at 5k.
Back 1994, I purchased a new 1995 Chevrolet Impala SS equipped with GM's LT1 engine and I took very good care of that car. Maybe too good care of that car. I was essentially wasting time and money as I would change the oil every 3,000 miles.
Where I was really stupid in this situation was that I was running Mobil 1 5W30 and a Mobil 1 oil filter (best oil filter available at the time) every 3,000 miles when I could have gone at least 2-3 times longer on the same oil and filter.
I ran 3,000 mile OCI with Mobil 1 5W30 and Mobil 1 oil filters from it's first oil change until the engine threw a rod at 75K miles. Who knows what caused the issue, but I doubt it was an oil related failure as I always had fresh oil and a new filter on that car. It was a shame as the GM LT1 engine was known to go a few hundred thousand miles without any issues. I just got a weak engine apparently.
Perhaps, Mobil 1 wasn't as good as you thought, and perhaps changing your oil so often at 3000 mile OCI you did more damage than good. Running the bearings dry for the startup time after an OC maybe had disastrous effect on bearing life.
Or you got a dud engine.