A funny observation i had made up here. Some of the big farmers that I know run conventional 15w40 year round in their big quad track tracters and combines. They run the combines full out for most of the day for weeks on end. The big tractors run some immense equipment and they run hard. No issues. The only reason I run semi synthetic is for cold start in the dead of winter.
Does a Turbo diesel engine NEED synthetic oil?
- Thread starter Redhawk454
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answer to question is NO a turbo doesn't require synthetic oil... and the old advice about letting the turbo have a cool down period is subjective and has many variables to consider ( many modern turbo's have liquid cooled bearing housing) that its not simple..
pulling a 12 ton trailer with your turbo diesel in 95F weather, yeah, let it cool down for a few minutes before you shut it off... but you drove to the local convenience store for a pack of smoke and turned right around and headed home, the last 1/2 mile at less than 30 mph on a side street, shut it off when you park it.. no sense un necessary idling.
pulling a 12 ton trailer with your turbo diesel in 95F weather, yeah, let it cool down for a few minutes before you shut it off... but you drove to the local convenience store for a pack of smoke and turned right around and headed home, the last 1/2 mile at less than 30 mph on a side street, shut it off when you park it.. no sense un necessary idling.
I use Mobil Delvac 1300 15w40 conventional oil in my Cummins Ram. I’ll be switching to Mystik synthetic blend on the next change. I don’t think you need synthetic oil in a turbo diesel. Like you noted let the vehicle idle to bring down temperatures prior to shutting it off. On my truck when I’m towing I shoot for less than 400F before shutting down. If I can get into the lower 300’s I even prefer that.
Just my $0.02
CleanSump
Site Donor 2022
Turbo Diesel Military trucks ran on conventional for decades with no problem. Straight SAE 30 at that.
I drove a few deuce and a halfs that were over 20 years old on the original engine.
I drove a few deuce and a halfs that were over 20 years old on the original engine.
Everyone makes very good and valid points. I prefer synthetic for the extra margin of safety (if you will) but any oil meeting the oem spec be it conventional or synthetic is going to work fine. I think operating the equipment correctly and changing oil frequently is more important then the oil itself (as long as it meets spec).
Public transit buses and trash trucks - two of the hardest use cases for a diesel engine also get regular UOAs and have large sumps as well, despite being driven hard and put away wet. A OTR big rig can see long stretches of highway for hours on end, a bus sees plenty of WOT. The local transit agency uses Chevron Delo 400 in their buses and does 3000-4000 mile OCIs.
local transit agency I worked for for 35 years used low bid 15w40 purchased in tanker truck sized allotments and really didn't have any oil related issues either.. and it was no name oil, probably never from the same supplier twice in a row... you are correct, a diesel bus or garbage truck use is about the most severe use most diesel engines see.. my son drove a tractor trailer, if he was partnered with a co driver that tractor trailer might not shut down for a week, just droned down the highway for hours on end, 24 hours a day .
A video from Chevron 5w40 vs 15w40.
"Synthetic Technology" is a synblend. Mobil's Delvac 1 range is fully synthetic if you want HDEO FS in Mobil they have Mobil Delvac 1 LE. However small passenger car all the way to midsize SUV diesels especially in the UK / Europe will do just fine on A3B4 or A5B5 5w30 or 5w40, you won't need a HDEO API C* spec for this.
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Most turbo chargers have coolant surrounding them now
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no, most do not run synthetic.
in truth I do not think any engine "Has" to have synthetic to run reliably. In fact I know of more instances where syn is not recommended, such as generators, etc small engines, and mazda rotary.
The hundredth monkey effect illustrated
I would like to know where it's not recommended for any OPE engine because in fact I've seen it recommended in manuals constantly based on what temp they will be operating in.
The rotary is a special case as earlier synthetic didn't burn completely in the combustion chamber and caused issues with apex seals. Easy fix is to disable the oil meter pump and use a 2 stroke oil which is the better idea anyway but the general public rarely checks their own oil so go figure.
Every turbo charger now has a coolant jacket surrounding it. The heat will auto-siphon away after the engine is turned off. Even more so most vehicles have an electric aux coolant pump that also does this in conjunction with the radiator fans. Case in point my Tiguan, driven normally in town I rarely hear it turn on after the vehicle is switched off. Driven aggressively I'll hear it every time.
Too another point just about every oil is synthetic to some point now anyway, the most important thing is it meets the manufacturer specs and is tailored for the environment it will operate in.
Too another point just about every oil is synthetic to some point now anyway, the most important thing is it meets the manufacturer specs and is tailored for the environment it will operate in.
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11,000 hours and 216,000 miles on my 6.7 cummins. Runs either delo or delvac. The delo started getting expensive so I've been running delvac recently
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The largest diesel engine manufacturer in the world, Kubota, does not spec synthetic. Not recommending and not requireing are two different things. Good enough?
That would be Caterpillar, not Kubota and no they don't spec it either but the advise 10w30 is lower temps vs 15w40 which sounds like an ideal environment for a 5w40 synthetic for easier starting in the cold.
Sure I guess...
The point you fail to grasp is if the basics specs can be met with a regular oil(which is semi-syn anyway) than yes synthetic is not needed but that by no way means it's warned against using and in fact based on the environment it may be operating in it may be recommended. Take standby home generators, perfectly fine operating on a 10w30 until the temp drops then 0/5w30 synthetic is recommended since they go full load after start much like many Kubota engines.It all comes down to cost vs. benefit and whether it actually will affect equipment life in the long run.
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Well until recently, I suppose, seems weird as they dominate the compact market and such, but ok you win.
Sure, maybe, but that is not what the spec say, which is too my point
Right so i own many Kubota products and have used ones owned by others for 20+ years, and 99% of the time, they run Kubota brand oil, with 100s of thousands of hours on them. Really the life of those machines is not the engine anyway. To your point, at least with Kubota, super udt2 is a "synthetic" fluid. Funny enough, my local Kubota dealer never changes the fluid, only the filter and top off.
All in all, I agree with you. Synthetic is better, especially these days with the price point, but I have seen no real difference in longevity using "dino" oil.
This is the real reason behind conventional oil's success in most diesel engines.
What oil did turbo diesels use before synthetics were widely available?
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