srah1953
Well-Known Member
What`s the principal difference between gear oil and engine oil? Can gear oil be substituted for engine oil or vice versa?
Thanks
Thanks
Engine oil vs transmission oil
- Thread starter srah1953
- Start date
Bobc
Well-Known Member
A lot of gearboxes run on engine oil (in fact the majority of cars use the engine oil to also lubricate the gearbox).
Not heard of gearbox oil being used in an engine though. I suspect the temperatures might be too high.
Not heard of gearbox oil being used in an engine though. I suspect the temperatures might be too high.
vyv_cox
Well-Known Member
The difference is that gear oil contains far higher loadings of additives, including boundary lubricants, ZDTP, anti-foam and many others. But the gearbox design determines what oil is needed, dependent upon tooth loadings and temperatures. So your second question is an impossible one to answer. Some boxes have low tooth loadings, e.g. the small Yanmar ones, whereas others may need highly loaded lubricants and even ATF, which is the highest loading of all.
anoccasionalyachtsman
Well-Known Member
I may be being a bit thick/senile, but I've never had a car with shared oils. Except Land Rovers. They distribute their oil everywhere.
VicS
Well-Known Member
Often very different viscosity. Gear oils having higher viscosities but see later comment
Different additives... engine oils contain detergents and acidity neutralisers to combat the contamination from combustion products etc Gear oils may contain additives to combat the high loads and wear in certain types of gear systems. There are different specifications for diesel and petrol engines although many engine oils are suitable for both
However you will often find gearboxes using exactly the same oil as the engine but I dont think you find many if any engines using gear oil
The SAE viscosities of engine oils and gear oils are measured at different temperatures so are not comparable ( an SAE50 gear oil does not have the same viscosity as aa SAE 50 engine oil)
Two stroke oils, automatic transmission oils and hydraulic oils are different yet again
Use the grade of oil specified by the engine or gearbox manufacturer
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Bobc
Well-Known Member
Some examples:-
https://www.quora.com/How-do-four-stroke-motorcycle-engines-with-a-shared-gearbox-lubricate-What-system-do-they-use
Most motorcycle engines share engine oil with gearbox oil, which means the oil has to do a different job than in an engine-only cases.
To add to this a lot of motorcycles use a “wet” clutch which is submerged in oil too.
In terms of the engine itself it doesn't really do much special, it will have a normal oil pump.
The magic happens in the oil, it is specially formulated for the application. It has additives to help the clutch while still maintaining a nice slick surface between the gears. This is why you should never use car oil in a motorbike, and also why the service intervals are shorter on a motorbike. Some bikes have service intervals measured in hours! (The KTM 500 EXC has a 30 hour service interval)
Fun fact, the classic mini also shares it's engine oil with the gearbox, but as the clutch is “dry” it can get away with normal car oil, albeit with a shorter service interval than a typical car.
ithet
Well-Known Member
My engine, Volvo Penta 2030D specifies either ATF or engine oil for its (ZF-Hurth) gearbox. When I enquired at the local VP agents I was told to use engine oil. I do not know if this was the best advice but it was not as a result of their stocks as they do sell VP priced ATF.
srah1953
Well-Known Member
Thank you very much for these.
I wasn't intending using an unspecified oil. It's that there have been problems with the cone clutch on the Yanmar SD 50 Saildrive (which I have). On another forum there were comments suggesting it would be better to use GL4 rather than GL5 gear oil. I can't see whether the Yanmar recommended Quicksilver High Performance Gear Lube is GL 4 or 5.
Anyway, it got me thinking ...
I wasn't intending using an unspecified oil. It's that there have been problems with the cone clutch on the Yanmar SD 50 Saildrive (which I have). On another forum there were comments suggesting it would be better to use GL4 rather than GL5 gear oil. I can't see whether the Yanmar recommended Quicksilver High Performance Gear Lube is GL 4 or 5.
Anyway, it got me thinking ...
Praxinoscope
Well-Known Member
My 1970 Mini Cooper S shared the engine oil with the gearbox as did all the original mini engines, don’t know if the modern BMW Mini’s use the same system.
anoccasionalyachtsman
Well-Known Member
Ahah, I think I knew and had forgotten about the Mini (never owned one and I'm too tall to enjoy driving them). Bikes I certainly knew about, rebuilt quite a few, but car-wise, apart from the A series engine are there any others?
rogerthebodger
Well-Known Member
The austin maxi was the ame and used the little known BMC E series with gearbox underneath.
Other than the additives the gear box viscosity with put excessive drag and reduction of oil pressure in a IC engine would cause problems.
RichardS
N/A
Perhaps because manual gearboxes are often filled for life these days, motorists don't realise that they have their own oil?
I changed the oil in my Mondeo gearbox a few months ago at 100,000 miles. It was a rather fiddly job that definitely needed an oil pump. I guess that Ford assume that it will probably never be changed so they don't need to make it easy. The oil I took out looked OK so I wished I'd not bothered although by then I'd bought the oil so I thought I might as well use it.
Richard
Balbas
Well-Known Member
Ahhhhh, typed two responśes, both deleted before posting. This website is rubbish.
Sealed for life - no, manufacturing spin designed for fleet buyers. Every car I've ever come across that has a sealed for life box has an approved way of changing the oil...
GL4 vs GL5. Can't remember which way around it is, but one has more of the additive which makes it stick to the gears. And which eats yellow metal bearings. So use the 'GL rating' your box manufacturer recommends.
Sealed for life - no, manufacturing spin designed for fleet buyers. Every car I've ever come across that has a sealed for life box has an approved way of changing the oil...
GL4 vs GL5. Can't remember which way around it is, but one has more of the additive which makes it stick to the gears. And which eats yellow metal bearings. So use the 'GL rating' your box manufacturer recommends.
Balbas
Well-Known Member
As for engine oil in a gearbox, I used to have a mate who designed gearboxes for a living. He used to describe the action of the gears as chopping up all of the molecular strands in the oil over time and said that gear oil was formulated especially to prevent this (or the gearbox designed to run on engine oil as in the Austin mini).
This isn't an academic article, but explains it how I remembered it being explained to me. I expect there are some peer reviewed articles out there for the finding. https://www.mototribology.com/articles/viscosity-modifiers-shear-stability/
Also, my old mate would get very vexed when people spoke of gear oil when they meant ATF. Apparently transmission oil (for planetary gear auto boxes) is very different to gear oil (or was 20 years ago when I knew him).
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fisherman
Well-Known Member
PRM box I had, 500n (https://www.prm-newage.com/p14-prm500) used engine oil. If a gearbox had been damaged or strained in some way the engineer used to pick up the oil and squeeze it to see if it had been degraded.
RichardS
N/A
I assume that is not a reply to my post as I didn't use the phrase "sealed for life" and I went on to explain that I changed to gearbox oil at 100k.
I'm sure that there is no technical reason with modern synthetic oils that gearboxes cannot effectively be filled for life. My new car's computer is projecting its very first oil and filter change at over 25,000 miles. If a high performance engine can manage that kind of mileage straight off the production line then a gearbox at 100k should be a doddle.
Richard
Balbas
Well-Known Member
my first response (deleted by this rubbish website) quoted your 'filled for life'. Engineers I know scoff at the idea. One makes his money as an 'expert witness' and sees many failed gearboxes that he tells me would have lived if they'd been serviced. Mainly LandRover Discoveries it seems, but then I own one and I think he likes to try to frighten me with all of the expensive failures which require the body to come off in order to fix (gearbox, turbo, parts of the exhaust system, brake pipes etc, not to mention crank failure, oil pump/cambelt failure, suspension faults etc, why do I do it to myself...?)I assume that is not a reply to my post as I didn't use the phrase "sealed for life" and I went on to explain that I changed to gearbox oil at 100k.
I'm sure that there is no technical reason with modern synthetic oils that gearboxes cannot effectively be filled for life. My new car's computer is projecting its very first oil and filter change at over 25,000 miles. If a high performance engine can manage that kind of mileage straight off the production line then a gearbox at 100k should be a doddle.
Richard
Another designs print heads for a living (as far as I can tell), but is a chartered engineer and worked in automotive for years. He has a 'megaflush' done regularly on his Range Rover and his Jag. Reckons the boxes shift much better and will last much longer - not that he'll ever find out, he doesn't keep them long enough.
Common theme JLR? Maybe, dunno. My old volvo (have an XC70 too for when the Landy breaks down!) really needs a megaflush too.
I challenge your 100k is 'life' though. That's what I mean by advertising puff for the fleet managers. Even Fords have 6 digits on the odo these days...
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RichardS
N/A
In general, manufacturers regard "life" as 100k miles/10 years, although, in the real world, we all know that cars will last much longer than that.
Richard
JumbleDuck
Well-Known Member
A pal of mine had a Rover 60 (P4) which had shared engine, gearbox and in his case overdrive oil. He used to take it into tyre places offering a flat rate oil change and watch their faces as they found it took five (iirc) gallons to fill the thing up.
My Yanmar 1GM10 manual specified the same oil for gearbox and engine, but it was just the same oil, not a shared sump.
coopec
N/A
Didn't the Mini Minor have a gearbox in the sump of the engine?
Before leaving Morris in 1952, he had already built a special Morris Minor with front-wheel drive and a transverse engine, and this idea was now applied to the new car. The masterstroke that made this engine installation possible was the idea of putting the gearbox in the sump of the engine. Other important space saving measures were the tiny 10 inch whee...
