Hey all, so I have a 2003 Highlander with the thirsty-for-oil 4 cylinder. It burns enough for me to add a quart of oil about every 300 miles or so.
I’m due for an oil change, I do it every 3000 miles because it’s a 200k mile car. I’m wondering if I should even change the oil since it’s always topped off with new stuff, or if I should just change the filter and not worry about the oil.
Any advice is appreciated.
TLDR: you should, 100%.
Three reasons:
Basically your oil is quite a complex liquid with lots of “designed” properties. It designed to last certain motor-hours (yep, 3k, 5k, 7k km is not a precise measure, but the simplest one). It has specific properties therefore it is best to keep oil non-mixtured with residuals, if possible.
Whenever your engine performs a combustion cycle a bit of metal particles here and there are left in the oil as a result. They tend to accumulate at a bottom tray, and in a filter. This process is cumulative – the more particles there, the mode damage will be done, as a result more particles will be emitted into the oil.
It is best to stick with your oil change schedule regardless. Would be also good to check where oil goes. Given the mileage it could be a gasket, piston rings. Better check it before it turned into something worse :)