Originally Posted by Cowboybart
On todays computer controlled engines, 10K is perfectly fine. There are many variables that go into determining your interval. Sump capacity is the biggest, also driving environment. If your sump holds 3.5 gallons, then you can go longer before your oil in contaminated. Oil doesn't "breakdown" or lose lubricating properties. Oil gets contaminated which can compromise it's lubricating properties. If you can keep it clean, you can run oil for 200K miles. How do you know if it is clean?? Not by looking at it, but by a lab doing an analysis on it. The cost of the analysis is about $35, so most people just change the oil, never knowing if it has silicon (dirt), fuel dilution, soot, coolant or other contaminants in it.
Once when I was bored to tears, I read how Detroit Diesel came up with a 15,000 change interval for their Series 60 engine. They put it under 100% load for 50% of the time and idled it for 50% of the time. Idling is not good for a diesel engine, and you have to go downhill sometime!!! My idle time is about 15% in winter and 7% in summer - I don't idle my truck. It is not at a 100% load all the time, I do go down hills too. I pull a sample at 15K and send it in. If it is good I keep going. I do change the filters at 30K as I have no way to tell if they are getting clogged. Because my engine has some age on it and a performance tune, I usually only get 45K-60K out of my oil. When I only had 200K - 400K on the engine, I once went for 186K on the same oil. The analysis came back good, but I changed it anyway.
All this means is that if everything is good, 10K is not a big deal in a gas 4L-7L engine. What it doesn't mean is that it will always be good. If you are sucking in unfiltered air and don't know it. You are doing damage going to 10K. If your headgasket is starting to fail and coolant is contaminating your oil, a 2K oil change interval isn't enough to keep damage from happening. If you have a performance chip and one of your injectors is starting to drip, in 3K your oil could be diluted enough that the viscosity is down to 2 or 3 weight oil!! All of the above problems can be detected on an oil analysis before major damage happens. Currently my Series 60 is producing 2.3% soot at 15,000 miles (over 2% is an issue). It could be the performance tune combined with a weak injector - which is an expensive fix. Or it could be the valves slightly out of adjustment. I will run the overhead and look at the next analysis. If it goes down or is only slightly higher - problem solved. If it is around 5% then it is time to change the oil and correct the problem (more than likely an injector).
I don't recommend you do an analysis on your Toyota every 10K, but I would certainly do one every 25K. Amsoil sells kits, Caterpillar has kits and Horizon labs can get you kits. All are good labs. Avoid benchtop instant analysis at a truck lube or truck stop. Bad information is worse than no information.



Like this man said. If your engine is leaking air, gas or anti freeze, you will need to change it every 1000 miles. If your engine is right, you can go a long ways before an oil change. I have gone 46K and then 39K between oil changes with Amsoil , filter every 15K anf oil test every 15K. The oil always came back good , even after 46K. I did this 10 yrs ago and still have the engine with 282,000 mi. and it burns about 1qt per 10,000 mi. I dont use Amsoil anymore cause Shell Rotella T6 is everywhere and its $40 for a 10 qt. jug on super sale. Now I chenge about every 12,000 mi. but I am going to get an oil test after 10K . Not to see if the oil is good, but to see if I am leaking diesel, anti freeze or dirty air.


But the fruits of the spirit is love, joy, peace, patience, kindness, goodness,faithfulness, Gentleness and self control. Against such things there is no law. Galations 5: 22&23