Gen4 replacing diff oil

Not sure about an oil that meets both GL4 & GL5 specification - it's either one or the other. Both have different properties and for a good reason!

At the end of the day, a Diff is a simple beast. GL5 oil is the industry standard for 99% of diffs. But you'll do no harm what so ever playing it safe and going with a GL4 if you're unsure.. I'm just frustrated with Suzuki because they've been deliberately 'non-committal'. I bet they wouldn't tell you what grade fluids they use at a Suzuki service station... Probably just standard grades out of a commercial drum like most garages....

The diff in the gen4 is the same as the gen3, which in turn was carried over from the SJ. They are tried and tested, very reliable and there's absolutely nothing fancy about it. Any gear oil will be fine. I use EP90 in mine, which is the gear oil used in almost all plant and agricultural machinery as well as industrial gearboxes. Basically, if it says gear oil on the bottle it will be fine.

Thanks, it's the curse of working in IT where you frequently need to get precisely the right 'thing' or something else doesn't work. It's a struggle for me to go for a good enough option! :silly:

DAGZOOK wrote: Not sure about an oil that meets both GL4 & GL5 specification - it's either one or the other. Both have different properties and for a good reason! ....

I believe it is possible, did some googling some time ago to find how such a thing is possible.
If I recall correctly corrosion inhibitors are added to GL5 to prevent possible yellow metal damage, so it's ok in GL4 applications.
So it's a battle of additives. I guess it's not a problem, but like antifreeze anti corrosion additives they don't last for ever, so sticking to a maintenance schedule is probably more important with combined spec gear oil.

So yes they do sell GL4 and GL5 spec gear oil.
Mike

I've come across GL4/GL5 combinations in marine applications so they can exist but I haven't used any. Chris

Three comments

1) Busta your comment was econonic in detail, therefore incorrect, to use an oil in a diff the oil has to adhere to the GL5 spec for the high shear stress that the hypoid gears put the oil the oil. Not any gear oil but one with a GL5 rating. A GL4 only spec oil will not be suitable in this case.

2) The GL5 oils has added sulphides to cover for the extra shear stress on the oil. In around 1954 the sulphides used to get the GL5 spec tended to shed sulphar out of solution and may well have dammaged gearbox yellow metals.

Since around 1957 oil blenders have used more stable sulphides in GL5 oils and I ask any person here that disagrees to provide a link to actual tests that show a modern GL5 oil ( made in the last 10 years) will damage gearbox internal.

Not a link to a similar comment that they damage yellow metal but show details of an actual lab test with a count of the yellow metals in the used oil analysis that is higher than a test in a similar gearbox that was run with a GL4 oil.

Hint, you wil not find such a test that produces these results.

In the past few years some companies have started using other additives other that these extra sulphides to obtain the additional properties required to obtain GL5 status while also having a GL4 qualification. Total of France being one. They will not advise the additives they use to make the oil a true GL4/GL5 specifications.

I have used my contacts in Total to try and tease the facts out but no info was given. Therefore yes there are now GL4/GL5 oils that do not have an additional sulphide load.

3) The Suzuki 75W oil mentioned in Jimny 4 handbook is a Suzuki specified 75W/80 GL4/GL5 oil. I assume using these new non additional sulphide additives.