- Joined
- Oct 19, 2022
- Messages
- 19
What can happen to a leaky engine if I just keep topping up the oil and not actually doing a drain and refill?
The car is a 2000 Mazda Miata with the BP4W iron block, aluminum head 1.8L engine. The engine is not original to the car, which I didn't realize until some time after purchasing the car back in 2019. Compression numbers are excellent, around 200 psi all across. Leakdown numbers are okay, 10-15% across the board. It leaks oil like crazy, but I do not see any visible smoke in the rear view when taking the car to redline.
I used to change the oil once a year since I only drive it about 5,000 miles a year. But the last time I actually did an oil change was August 2021. Since then I've added a full quart of Mobil1 AFE 0w30 SEVEN TIMES now, in less than 7K miles. Filter issues aside (I know I need to change the filter), what can happen if I don't fully drain the oil and replace with the usual 4 quart capacity? Seeing as how I've added 7 quarts, those 4 quarts I put in 15 months ago is pretty much gone for all intents and purposes.
I do have plans to pull the drivetrain out this winter, and re-seal the entire engine. Front to back, top to bottom. Both crank seals, flywheel bolt sealant, oil pan lip seals, new oil pan sealant, camshaft seals, cam cover gasket, oil cooler o-ring, and anything else I can find associated with sealing the oil inside the engine. After that I will obviously go back to regular oil changes. And given that I'll be draining the oil in the next couple of months before pulling the engine, I don't see any point in changing the oil now, only to drain it yet again at that time.
I will also take a sample of the oil that comes out and get a UOA of that oil, while I have the engine and drivetrain all apart.
The car has about 172K miles on it, but unfortunately I have no idea how many miles are on the engine, or if it's ever been rebuilt.
The car is a 2000 Mazda Miata with the BP4W iron block, aluminum head 1.8L engine. The engine is not original to the car, which I didn't realize until some time after purchasing the car back in 2019. Compression numbers are excellent, around 200 psi all across. Leakdown numbers are okay, 10-15% across the board. It leaks oil like crazy, but I do not see any visible smoke in the rear view when taking the car to redline.
I used to change the oil once a year since I only drive it about 5,000 miles a year. But the last time I actually did an oil change was August 2021. Since then I've added a full quart of Mobil1 AFE 0w30 SEVEN TIMES now, in less than 7K miles. Filter issues aside (I know I need to change the filter), what can happen if I don't fully drain the oil and replace with the usual 4 quart capacity? Seeing as how I've added 7 quarts, those 4 quarts I put in 15 months ago is pretty much gone for all intents and purposes.
I do have plans to pull the drivetrain out this winter, and re-seal the entire engine. Front to back, top to bottom. Both crank seals, flywheel bolt sealant, oil pan lip seals, new oil pan sealant, camshaft seals, cam cover gasket, oil cooler o-ring, and anything else I can find associated with sealing the oil inside the engine. After that I will obviously go back to regular oil changes. And given that I'll be draining the oil in the next couple of months before pulling the engine, I don't see any point in changing the oil now, only to drain it yet again at that time.
I will also take a sample of the oil that comes out and get a UOA of that oil, while I have the engine and drivetrain all apart.
The car has about 172K miles on it, but unfortunately I have no idea how many miles are on the engine, or if it's ever been rebuilt.