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Ridin Dirty

helical lsd diff oil

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hey guys i have a jap spec-r s15 with a stock helical lsd and im just about to change my diff oil on the silvia and wanted to know 2 things.

1. should i use the 80w-90 recommended by the manual or will 80w-140 be ok to use aswell ?

2. whats the difference in using mineral diff oil as opposed to full synthetic diff oil ?

 

cheers heaps guys :)

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ok so is there a difference between 80w-90 mineral and 80w-90 synthetic oil ??

which one should i be using ?

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tossing up between an 80w-90 mineral or 75w-90 full synthetic. whats the general oil people use for their helical lsd ??

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anything, its just got gears inside that turn and shit, only use proper oil in a clutch type LSD or else you risk blowing up your penis

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Just did mine on the weekend. Castrol LSX 90, I already had 2l so the choice was made for me.

 

Mineral oil is something they dig up from the ground and then refine and filter out as much crap as possible before mixing in additives. Typically you are left with a mixture of many types of oil molecules (some good, some OK and some crappy), phosphorus, sulfur and various metals as contaminants. During use both the additives and the crappy part of the base oil breaks down due to shear loads and temperature.

 

Synthetic consists of 100% pure man-made oil molecules as the base (the blend is controlled for the required performance characteristics - but in general they don't blend in the crappy molecules) with additives mixed in. The base has no contaminants and no crappy oil molecules. During use only really the additives break down, the base oil is virtually indestructible (depending in blend).

 

Semi-synthetic is just adding some man-made oil molecules to mineral oil to reduce the percentage of crappy oil molecules.

 

The diff has a magnetic drain plug, clean it well to remove any collected metal particles. All types of oil equally get contaminated with fine metal particles and other crap. You rely on the additives to control this.

 

A tip for removing the filler plug (and this is the first one you should remove, because if you can't you should abort the job) is to use a couple of long extension bars threaded above the sub-frame and get a breaker bar onto them from the left side of the sub-frame. Alternatively if you can find a sump plug socket (like a very very short extension bar) you can probably get the breaker bar onto it closer to the diff. Also torque up the plugs to the low end of the range (39Nm ~ 29 ft-lbs) so they are not as hard to remove next time.

 

You will need some sort of pump to put the new oil back into the diff, there is no room for pouring from a bottle. I bought a 500ml syringe style pump and transferred from bottle to diff.

 

[Edit: Some 1:30am crappiness got in]

Edited by stockblues15

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ok i ended up getting full synthetic 75w-90 which should be good to use in the gearbox aswell if im not mistaken, might have to go buy some more tools to get the plugs on the diff out. cheers heaps guys

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use only gl 4 in diff, castrol is the goods, get some nulon treatment as well, makes gearbox feel more durable, not sure if it has a difference on wear etc but everytime I shift that stick my penis goes up and flacid a few times

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so i shouldnt use gl-4 in the diff.. ? i got gl-5 oil for the diff and am having trouble finding gl-4 for the gearbox...

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You might find 75W-85 full synthetic is GL-4 rated. It seems to be that way for both Nulon and Penrite, they don't have a GL-4 rated 75W-90 available. Not sure if there is any issue using 85 weight instead of 90 in the gearbox.

 

Some manufacturers claim their GL-5 oil is safe for use in synchromesh gearboxes and won't attack the white metal. You could check on their website to see if they state that for the oil you have.

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if you cant find anything throw some redline shockproof blue smurfs blood shit in there, itll cost you $75 + shipping but isnt necessary, castrol v something something is good shit, gl 4, throw penrite limslip in the diff or just penrite gear oil with limslip additive, its fvcking brilliant and cheap, you wont have to service your helical often as well which is good, to clarify, GL5 in diff, GL4- Gearbox, Penis- in your face you rooted KENTTT!!

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I've used Castrol and Red Line in the past in both diff and gearbox and I still think Motul Gear 300 has been the best by far.

 

Smoothest shifting cold or hot and made everything a bit quieter too

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