A couple of tips to pick up the best results with long drain synthetic lubes, based on 25 years of "lessons learned":
1) Start with a clean engine - I typically use the Amsoil engine flush if the engine had over 30k using petroleum oil. For high mileage engines, I now highly recommend the use of AutoRX. Use a double treatment if the engine is really dirty.
2) Make sure you aren't getting abnormal contamination, particularly from coolant, silicon or fuel. Do an oil analysis BEFORE putting the expensive synthetic in and trying to run a long change interval. A significant coolant leak can cause the oil to badly sludge up in 2k-3k miles and destroy the main bearings.
3) Tune the engine on a regular basis - this includes things like changing PCV valves and oxygen sensors and servicing EGR valves where required. A poorly running engine produces abnormal rates of oxidation and nitration.
4) Flush and refill the coolant every few years - If the engine is running hot from a clogged cooling system, the oil will oxidize more quickly.
5) Use an effective fuel injector cleaner on a regular basis, at least 1-2 times a year. I"ve had excellent results with the Amsoil performance improver. The Schaeffers Neutra and Redline SL-1 are also very effective. Chevron "techron' is probably one of the best off the shelf cleaners.
6) Get at least 10,000 miles on the engine before running a long drain interval. New engines don't have a very good piston ring seal and there is too much wear in the first 10k miles to keep the oil in for long periods. I will get 5k-6k on the motor before using a synthetic for the first time and limit the first Amsoil change to 7500 miles after that.
On the rare occasions where I see problems with Amsoil and extended drains, it is generally due to one or more of the above reasons ....
TooSlick
Dixie Synthetics
1) Start with a clean engine - I typically use the Amsoil engine flush if the engine had over 30k using petroleum oil. For high mileage engines, I now highly recommend the use of AutoRX. Use a double treatment if the engine is really dirty.
2) Make sure you aren't getting abnormal contamination, particularly from coolant, silicon or fuel. Do an oil analysis BEFORE putting the expensive synthetic in and trying to run a long change interval. A significant coolant leak can cause the oil to badly sludge up in 2k-3k miles and destroy the main bearings.
3) Tune the engine on a regular basis - this includes things like changing PCV valves and oxygen sensors and servicing EGR valves where required. A poorly running engine produces abnormal rates of oxidation and nitration.
4) Flush and refill the coolant every few years - If the engine is running hot from a clogged cooling system, the oil will oxidize more quickly.
5) Use an effective fuel injector cleaner on a regular basis, at least 1-2 times a year. I"ve had excellent results with the Amsoil performance improver. The Schaeffers Neutra and Redline SL-1 are also very effective. Chevron "techron' is probably one of the best off the shelf cleaners.
6) Get at least 10,000 miles on the engine before running a long drain interval. New engines don't have a very good piston ring seal and there is too much wear in the first 10k miles to keep the oil in for long periods. I will get 5k-6k on the motor before using a synthetic for the first time and limit the first Amsoil change to 7500 miles after that.
On the rare occasions where I see problems with Amsoil and extended drains, it is generally due to one or more of the above reasons ....
TooSlick
Dixie Synthetics