Motor oil and Turbo's

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Back in the 1980's the big deal was that a turbocharged engine would "cook" the motor oil esp on shut down after a hard drive. Is this still a concern with modern oil and modern engines? And over time will the turbo in a modern engine cause modern oils to get so hot that it creates engine deposits from the high temps?
 
Modern engines have additional electric pumps wich help to cool down turbo after a shutdown...either via engine oil...antifreeze or both combined...
 
Like KameleON said, most have gotten much better. For one, oils have gotten better to deal with the extreme temps. And most modern turbos have electric pumps to continue cycling coolant through the turbo after shutoff.

My SRT neon had a "turbo timer" which would keep the engine running for a bit after shutting off to continue cycling oil. My SRT caliber had the water pump, and so now does my GTI. In my VWs manual is still recommends letting the car idle for a period of time after hard driving, even with that electric pump.

I basically always wait 30 seconds or so before shutting down.
 
I think I read that my turbo was designed to have a slow gravity feed of coolant and/or oil after shutdown to help avoid coking...I actually don't know exactly where the turbo is without looking it up, but I think it sits pretty low in the engine.
I also hear a pump running sometimes after I shut down, but I don't know if that's for the turbo.

dexos1 Gen 2 actually has a test for turbo deposits, another reason I look for that standard on the oils I buy. HTO-06 probably covers that too, but for an earlier generation of turbo (2.3l in the Acura RDX introduced in 2007) and I'm not sure how many makers are still testing for this standard...some people like that used oil must be tested to get this approval.
 
There's a simpler method that doesn't require a electric water pump; this is done by moving the highest point of the coolant system off the radiator to another small reservoir that now has the "radiator cap" above the turbo - via convection it draws cooler coolant as the coolant in the turbo bearing pack starts to boil off when the engine is shut down - the technical term is called thermal siphoning. The bearings really never get hotter than the boiling point of coolant which is around 250f -/+ with a 50/50 coolant mix.

Here is a white paper on it from Garrett

https://www.turbobygarrett.com/turbobyga...ter_Cooling.pdf
 
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Originally Posted By: Tiir
There's a simpler method that doesn't require a electric water pump; this is done by moving the highest point of the coolant system off the radiator to another small reservoir that now has the "radiator cap" above the turbo - via convection it draws cooler coolant as the coolant in the turbo bearing pack starts to boil off when the engine is shut down - the technical term is called thermal siphoning. The bearings really never get hotter than the boiling point of coolant which is around 250f -/+ with a 50/50 coolant mix.

Here is a white paper on it from Garrett

https://www.turbobygarrett.com/turbobyga...ter_Cooling.pdf


Great post! Thanks for the info.
I would guess this is what I interpreted as a gravity feed in my engine, but it sounds like it's really thermally driven.
 
Short answer: yes, manufacturers have improved turbo lubrication and cooling so the average consumer (that doesn't read or comprehend the owner's manual) doesn't kill them quite as quickly. A turbo will still put more stress on the oil, but between oil chemistry improvement and the afore mentioned engine design changes a modern turbocharged car is not inherently fragile.
 
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And, in the old days they mounted turbo's so the oil drain was not vertical out the bottom. Very important. So they would have the oil drain clocked at whatever angle was convenient for MFG. But that allowed oil to collect and sit there in the turbo bearing cavity and cook.

All modern turbos have the oil drain directly out the bottom so they empty. The only oil to "cook" is the residual film in the bearing.

If you've let it idle while parking or maneuvering, it's cool enough to be fine. Just don't go up hill at 1,200*F (EGT) and then just shut it off ...
 
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Originally Posted By: BrocLuno
And, in the old days they mounted turbo's so the oil drain was not vertical out the bottom. Very important. So they would have the oil drain clocked at whatever angle was convenient for MFG. But that allowed oil to collect and sit there in the turbo bearing cavity and cook.

All modern turbos have the oil drain directly out the bottom so they empty. The only oil to "cook" is the residual film in the bearing.

If you've let it idle while parking or maneuvering, it's cool enough to be fine. Just don't go up hill at 1,200*F (EGT) and then just shut it off ...
This !!!
 
Depends on what kind of cars or trucks? Whether it is designed properly or not.
 
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Oils and Turbo's have improved significantly since the 1980's. I never had a turbo problem with my 2004 Passat in 14 years of ownership and I never, ever bothered to let it idle before shutting down. Kendall GT1 full synthetic 5W40 for virtually all 14 years.

I guess the only people who might need that "cool down" advice would have to have a residence with a 35% grade x 100+ foot driveway before the garage?
 
Originally Posted By: lexus114
what i don't understand is. my lexus nx is turbocharged and lexus STILL recommends a 10,000 mile oi change interval?


That engine is stressed [with me driving]. If you don't trust them, take a sample, look to see if it is oxidized beyond reasonable level after 10k. I'm ok with 10k oci, but my engine rus (if at all) with little stress just supplementing the electric chariot.
 
Originally Posted By: Dyusik
Originally Posted By: lexus114
what i don't understand is. my lexus nx is turbocharged and lexus STILL recommends a 10,000 mile oi change interval?


That engine is stressed [with me driving]. If you don't trust them, take a sample, look to see if it is oxidized beyond reasonable level after 10k. I'm ok with 10k oci, but my engine rus (if at all) with little stress just supplementing the electric chariot.



yes, i have a blackstone kit in my tool box. so when i change it, it will be sent out...
 
Originally Posted By: lexus114
what i don't understand is. my lexus nx is turbocharged and lexus STILL recommends a 10,000 mile oi change interval?



Your Lexus NX is also one of the modern vehicle that states in the manual for high load driving e.g steep hills, race track, or towing a trailer that a idle time is recommended for approximately 1 minute - it's at page 139 of your owners manual.
 
Originally Posted By: Tiir
Originally Posted By: lexus114
what i don't understand is. my lexus nx is turbocharged and lexus STILL recommends a 10,000 mile oi change interval?



Your Lexus NX is also one of the modern vehicle that states in the manual for high load driving e.g steep hills, race track, or towing a trailer that a idle time is recommended for approximately 1 minute - it's at page 139 of your owners manual.


i will check that, thank you. but i usually give it 30 seconds before i shut it off..
 
Originally Posted By: lexus114
what i don't understand is. my lexus nx is turbocharged and lexus STILL recommends a 10,000 mile oi change interval?

They bank on you trading it off for something new, or putting low miles on until it's out of warranty?
wink.gif
 
Back in the good old days (or were they really that good?) turbochargers were (in most cases) not water cooled. Even today some rather modern VW diesels (2.0L BKD springs to mind) have only oil cooled turbos. Not surprisingly it's these oil only cooled units that exhibit the most failures. As on shutdown there is no water to stabilize temps at or below 100C.

On large diesel fleet oil only cooled is still rather common. I know that the workshop manager at the mine I work in kicks up a huge stink if the haul truck drivers don't let the engines idle down for 5-minutes.

Given I've been driving a turbo charged petrol cars daily for the last 12 years here are my tips.
-If the exhaust housing is glowing red from copping a beating. Best let it cool down a little before you turn it off.
-If you're just highway cruising or pottering around town, don't even think about it.
-Use high quality Synthetic oils (Helix Ultra for me or similar to manufacturer specification.
-Change at 5-10,000kms intervals depending on vechicle usage. Oil is cheap, turbo's are not. even the smallest amount of grit can damage bearings in turbo's. Clean oil (and blow off valves) keep turbos from destroying themselves.

I personally maintain (from my experience) that my fuel economy begins to deteriorate beyond ~5,000kms (in my turbo Saab 95.) Sure the oil will go another 5k. but with the increased fuel burn, I'm better off changing it out as I make it back in fuel savings. And that's at Aussie Oil prices
wink.gif
Seen too many people wait out oil changes on turbo vehicles to save a few penny's only to have to spend real $$ replacing a turbo.

Keep Boosting
Jordan
 
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