Turbo Rules Different Between PCMO and HDEO?

[RamFan]

I've noticed that on the PCMO side of this forum a common idea is present. Turbo engine = synthetic oil need.

On the HDEO side however, a lot, if not most of you guys use conventional in your turbocharged diesels.

Is there a difference in the turbo systems between the gas and diesel engines that makes synthetic in one more relevant than the other?

 

[440Magnum]

Just my opinion, but I do think gasoline turbochargers take a worse beating than diesel turbos. Mainly due to heat soak- Gasoline turbos are air-starved during idle and light throttle operation. Diesels run un-throttled, so at idle there is still a massive flow of relatively cool exhaust through the turbocharger on a diesel engine. A turbo glowing red hot from running under heavy load will cool down FAR faster at idle on a diesel than a turbo on a gasoline engine will, just because of the higher air flow.

Besides, gasoline turbos are, generally speaking, only built for providing boost during relatively short bursts of power. Diesel turbos are built to provide high boost for hours on end. They have better oil flow and better cooling than many gasoline turbochargers do.

 

[artificialist]

The exhaust gas temperature from a gasoline engine is significantly higher than that of a diesel. That is why in many diesels, conventional oil is okay, but in certain gas engines the stuff easily turns to sludge.

That in mind, some gas engines were okay with the stuff. I guess with enough of an oil cooler, and enough engine coolant also cooling the turbo bearings, things were okay.

Also, it depends on what diesel you have. Many European made diesels require a full synthetic.

 

[JHZR2]

Temperature, design, sump capacity, oil viscosity, user care.

 

[Gokhan]

All HDEOs have been required to work with turbochargers according to API Cx-y specifications.

Aren't now all (even dino) PCMOs also required to work with turbocharges after the ILSAC GF-5 specifications? See this GF-5 presentation (Page 14).

 

[Steve S]

Originally Posted By: artificialist
Also, it depends on what diesel you have. Many European made diesels require a full synthetic.

What are the oil change intervals in those engines?

 

[Steve S]

Usually the big diesel engines are idled till the exhaust gas temps are at a safe level to shut down the engine so the oil doesn't coke in the turbo bearings.

 

[Gokhan]

Originally Posted By: Gokhan
All HDEOs have been required to work with turbochargers according to API Cx-y specifications.

Aren't now all (even dino) PCMOs also required to work with turbocharges after the ILSAC GF-5 specifications? See this GF-5 presentation (Page 14).

The test that evaluates turbocharger performance in GF-5 is thermo-oxidation engine-oil simulation test (TEOST) 33C (ASTM 6335). See this link (Page 7) for the explanation of TEOST 33C in GF-5.

GF-2 had a turbocharger-protection requirement and this test was included in GF-2 with a 60 mg limit. GF-3 and GF-4 omit the test and there was no turbocharger-protection requirement in GF-3 and GF-4. GF-5 included the test again and the final specification put the limit at 30 mg in GF-5.

The long story short, all GF-5 dino or synthetic oils should be OK with turbochargers in gasoline engines.

 

[Steve S]

GF5 oils seem super.

 

[Gokhan]

Originally Posted By: Gokhan
Originally Posted By: Gokhan
All HDEOs have been required to work with turbochargers according to API Cx-y specifications.

Aren't now all (even dino) PCMOs also required to work with turbocharges after the ILSAC GF-5 specifications? See this GF-5 presentation (Page 14).

The test that evaluates turbocharger performance in GF-5 is thermo-oxidation engine-oil simulation test (TEOST) 33C (ASTM 6335). See this link (Page 7) for the explanation of TEOST 33C in GF-5.

GF-2 had a turbocharger-protection requirement and this test was included in GF-2 with a 60 mg limit. GF-3 and GF-4 omit the test and there was no turbocharger-protection requirement in GF-3 and GF-4. GF-5 included the test again and the final specification put the limit at 30 mg in GF-5.

The long story short, all GF-5 dino or synthetic oils should be OK with turbochargers in gasoline engines.

Note that 0W-20 GF-5 oils are exempt from TEOST 33C; therefore, do not use SAE 0W-20 in turbocharged engines unless it carries an additional manufacturer-specific certification pertinent to your turbocharged engine.

 

[A_Harman]

The biggest difference in gas and diesel turbo systems is that diesels rarely exceed 1250F exhaust temperatures into the turbine. Turbo gasoline engines easily exceed 1650F, and I have heard of engines going as high as 1850F. If a gasoline engine is shut down from high power without letting the turbo cool, the oil in the bearings will become subject to coking. Gasoline turbos are very often built with water-cooled bearing housings to protect the oil and bearings from overheating on a hot soak.

 

[Gene K]

Maximum sustained for a Detroit Series 60 is around 1050F I believe.

 

[ac_tc]

While the big dieselturbo may have lower peak temperatures they
are subjected to much moore time under load with
high thermal load.
Now i´m guessing but i suspect that the turbo requierments
are harder for a HDEO than a PCMO, turbos have always been there
and so have heavy loads on the engines.
We have also seen atleast a couple of EVO´s/ Impreza etc
that used HDEO with no ill effects exept keeping the
owners vallet a bit heavier due to lower price.
For some reason i belive that they also tend to be driven
rather spirited...and the temp goes up.
The lower exhaust temps on diesels are atleast to some part
related to engine longlivety( re: detuning), i suspect that a passcar diesel are allowed to peak higher since it doesent have to last as long as its bigger cousins.
If we would design a gas engine for a 500 kmile lifespan im
pretty sure that we wouldnt allow high exhaust temps..
We would prolly end up with a 100 hp /6.

 

[RamFan]

Thanks for the posts guys. Got a lot of info out of this one

 

[BMWTurboDzl]

Originally Posted By: Steve S
Originally Posted By: artificialist
Also, it depends on what diesel you have. Many European made diesels require a full synthetic.

What are the oil change intervals in those engines?
approx 12-10k miles.

 

[sittingduck57]

Most HDEO's are severly hydrocracked+ the average big rig capacity (including filter) is around 10 gallons

 

[sittingduck57]

Most HDEO's are severly hydrocracked+ the average big rig capacity (including filter) is around 10 gallons. Many have heat exchangers that heat the fuel/cool the oil.