Hi guys. I changed the gearbox oil in the 350z the other day and just need some views on the problem I had. Some threads on here say the manual transmission takes 2.9 litres. I found it took about 3.25 litres. So here is the problem.....I have 3 litres of Comma 75 90 gl4 fully synthetic in the gearbox but had to top up with a 75 90 semi synthetic gl5 Comma oil. So in short I have 3 litres of fully synthetic gl4 and 250 ml of semi synthetic gl5. Will this be a problem guys or do you think this will be ok. Not ideal I know but I was conscious of filling up the oil level until it dripped from the fill plug point.
I hear lots of problems arising from synchromesh and gl5 oils. Are they true?
Is my scenario acceptable.?
Thanks in advance.

 

Your call, you didn't up the levels too much but it will still have more sulfur/phosphorous

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GL5-rated gearbox lubricants will erode the soft metals like brass in your gearbox. I suggest a GL4 synthetic like Redline MT85 for Z33 gearboxes.

 

As dkmura says, yes, it's true that GL-5 and brass synchros aren't friendly but the real question is: will having 1/13th or 7.69% of your gear oil be GL-5 harm anything? Nahhhhh..... not significant enough to cause any damage. If you're concerned, drain a quart and refill with GL-4 to further increase dilution. If you're REALLY concerned to the point of panic attacks, you know what you need to do.

 

Hi guys. Thanks for the remarks. I rang the service department in Nissan also to clarify. They didn't seem to worried about the situation either to be truthful. However the thing is is that the gl4 has 0.05 per cent phosphor and the gl5 has 0.04 per cent phosphor so less phosphor in the gl5 which is strange.

 

The main difference in GL-4 vs. GL-5 are the pressure related compounds in the latter. GL-5 lubricants are designed to be used in differentials and other areas where the teeth on (larger) gears come under enormous loads. These type of compounds (not only phosphorous), are known to degrade the surfaces of softer metals, like they type found in six-speed transmissions.

As Mic has pointed out, there's likely no harm with the small amount you've added, but how many gearboxes have been needlessly damaged by the use of the wrong lubricant?