279,000 miles - Mitsubishi Mirage engine teardown - top end vs pistons

[buster]

Notice how the clean the top end is, but also notice how bad the pistons looked.

(6K km/3,728 miles) OCI's 0W20 full synthetic Dexos1Gen2. Motor used oil, rings packed and stuck and skirts/bores badly worn and one wristpin looking bad. Short OCI, Dexos oil. The car is one of a fleet of his delivery vehicles he services and maintains.

 

[Zee09]

Thread '2015 Mitsubishi Mirage high mileage 1.2 Ltr. engine tear down' https://bobistheoilguy.com/forums/t...high-mileage-1-2-ltr-engine-tear-down.379874/

 

[buster]

Gracias.

 

[nascarnation]

Coming from an era when "useful life" of a passenger vehicle was typically around 100,000 miles, I'll say "well done" to Mitsubishi and the fellows doing maintenance on this fleet.

 

[JTK]

Coming from an era when "useful life" of a passenger vehicle was typically around 100,000 miles, I'll say "well done" to Mitsubishi and the fellows doing maintenance on this fleet.

For sure on that. Nearly 300K miles on an extreme econo car engine. This thing more than did it's job IMO.

 

[buster]

Definitely a lot of miles. You could also argue a better oil would have prevented the pistons from gumming up which is when the car started to consume oil. 3k miles is also very frequent changes for a delivery vehicle.

 

[paulri]

Piston is right around 13:30 and after, but you can see the pic taken from the video in the OP.

 

[paulri]

Didn't watch the video, just fast forwarded to see how bad the pistons looked after a sparkling clean top end.

Did he say when oil consumption started, or how much it was consuming?

Definitely a lot of miles. You could also argue a better oil would have prevented the pistons from gumming up which is when the car started to consume oil. 3k miles is also very frequent changes for a delivery vehicle.

 

[Zee09]

Don't forget it probably idled a ton too.

 

[Azimuth]

Definitely a lot of miles. You could also argue a better oil would have prevented the pistons from gumming up which is when the car started to consume oil. 3k miles is also very frequent changes for a delivery vehicle.

Not to start a thin vs thick debate, but by "better oil" do you mean something like HPL/Amsoil/etc. or also a thicker grade like 5W-30?

 

[buster]

Not to start a thin vs thick debate, but by "better oil" do you mean something like HPL/Amsoil/etc. or also a thicker grade like 5W-30?

Right, something along those lines. The intervals were only 3,700 miles. Pistons don't look that good for such short changes IMO. However the car did run for 270k miles so it's hard to really complain.

 

[KEVINK0000]

Pistons look like garbage. Not sure if any oil would prevent. Looks like very low flow/movement/windage/aeration/drainage to those areas. Factory problem in my view. Mileage not enough to have that much deposit build.

 

[paulri]

Are you saying that because the gunk blocked off paths for the oil? Or that the paths weren't there, or were too small, to begin with?

EDIT: Never mind, you said "factory problem." that means it was poor design or manufacturing.

Pistons look like garbage. Not sure if any oil would prevent. Looks like very low flow/movement/windage/aeration/drainage to those areas. Factory problem in my view. Mileage not enough to have that much deposit build.

 

[KEVINK0000]

It is like an oil leak on an engine. Some leaks weep or flow so little they collect dust. Some flow more than that and collect a mountain of dust. Some flow enough to be clean of all dust, with just fresh oil in the leak area. Those pistons got enough oil to continue to build deposits, but not enough to continually wash away and have detergents be effective and keep deposits in suspension. Plus, significant blowby likely present after a time accelerated deposit build. So no oil difference would help, even a "cleaning" oil. Not enough flow to that area to help. Just my $.02.

 

[wwillson]

Pistons get very hot. I have said many times on this site that if you expect to get hundreds of thousands of miles on an engine without oil consumption, you have to keep the pistons, ring grooves, and ring lands clean. If you don't, then you get vertical scoring like you see in these cylinders because the oil control ring is packed with carbon. What ever oil was run couldn't handle the heat. Oxidative stability of the engine oil matters. If you trade cars often or lease, then it doesn't matter, but if you keep your vehicles for a long time and expect low oil consumption, then you gotta use an exceptional oil.

 

[Glenda W.]

Pistons get very hot. I have said many times on this site that if you expect to get hundreds of thousands of miles on an engine without oil consumption, you have to keep the pistons, ring grooves, and ring lands clean. If you don't you get vertical scoring like you see in these cylinders because the oil control ring is packed with carbon. What ever oil was run couldn't handle the heat. Oxidative stability of the engine oil matters. If you trade cars often or lease, then it doesn't matter, but if you keep your vehicles for a long time and expect low oil consumption, then you gotta use an exceptional oil.

I’d love to see how the pistons looked with HPL, Amsoil or other like high quality oils.

 

[buster]

Pistons get very hot. I have said many times on this site that if you expect to get hundreds of thousands of miles on an engine without oil consumption, you have to keep the pistons, ring grooves, and ring lands clean. If you don't you get vertical scoring like you see in these cylinders because the oil control ring is packed with carbon. What ever oil was run couldn't handle the heat. Oxidative stability of the engine oil matters. If you trade cars often or lease, then it doesn't matter, but if you keep your vehicles for a long time and expect low oil consumption, then you gotta use an exceptional oil.

Exactly.

 

[BMWTurboDzl]

Overall looks fine based on the mileage (270k miles) and the fact that it's a gutless 3-cylinder. I wonder if this engine has piston squirters? My guess is no. It would be curious know what oil they used.

I've driven a car with a 3-cylinder and it is a gutless as can be. My wife rev'd the daylights out of that thing trying to drive around Las Vegas.

 

[wwillson]

Pistons look like garbage. Not sure if any oil would prevent. Looks like very low flow/movement/windage/aeration/drainage to those areas. Factory problem in my view. Mileage not enough to have that much deposit build.

Does anyone know if this engine has oil squirters for the pistons?

 

[KEVINK0000]

I still think no different oil would have helped in this case. It is a factory problem. Pistons get hot, yes, but a stagnant oil film will just cook on a piston, even with the best oil available. The hot oil must be migrated to the sump and replaced. Clearly that wasn't happening, for a long time. Very doubtful if it is just piston/ring design either.