DRD Posted October 20, 2020 Report Share Posted October 20, 2020 Hi All, I thought its about time to change my diff oil. Last time I used 80w/90 oil but now 85W/140 has come up as the recommended oil. Any idea what's best to go for? Cheers Quote Link to post Share on other sites
Mick Forey Posted October 20, 2020 Report Share Posted October 20, 2020 Stick to EP90 as specified by Triumph. Available everywhere and works well. Mick Quote Link to post Share on other sites
Kevo_6 Posted October 20, 2020 Report Share Posted October 20, 2020 7 hours ago, DRD said: Hi All, I thought its about time to change my diff oil. Last time I used 80w/90 oil but now 85W/140 has come up as the recommended oil. Any idea what's best to go for? Cheers Hi, I use Penrite Mild EP as recommended by my Diff rebuilder. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 20, 2020 Report Share Posted October 20, 2020 (edited) Spec.  GL4 should be used as GL 5 is said to eat the yellow metal thrust washers on the sun and planet differential gears. Peter W PS.  How do you get the oil out your axle.  Do you have a drain plug or use a suction method? Edited October 20, 2020 by BlueTR3A-5EKT Quote Link to post Share on other sites
Mike C Posted October 20, 2020 Report Share Posted October 20, 2020 37 minutes ago, BlueTR3A-5EKT said: Spec.  GL4 should be used as GL 5 is said to eat the yellow metal thrust washers on the sun and planet differential gears. Peter W PS.  How do you get the oil out your axle.  Do you have a drain plug or use a suction method? GL5 EP oil must be used for the diff because of the extreme pressure of the sliding friction on the  hypoid gear teeth. Note it's these anti friction additives in GL5 that will render your gearbox synchro's near useless - so I use GL4 in the gearbox Quote Link to post Share on other sites
DRD Posted October 20, 2020 Author Report Share Posted October 20, 2020 59 minutes ago, BlueTR3A-5EKT said: Spec.  GL4 should be used as GL 5 is said to eat the yellow metal thrust washers on the sun and planet differential gears. Peter W PS.  How do you get the oil out your axle.  Do you have a drain plug or use a suction method? I use a large suction cylinder. Quote Link to post Share on other sites
Mike C Posted October 20, 2020 Report Share Posted October 20, 2020 "I use a large suction cylinder."- I use one of these but the oil must be warm. Quote Link to post Share on other sites
JochemsTR Posted October 21, 2020 Report Share Posted October 21, 2020 7 hours ago, Mike C said: GL5 EP oil must be used for the diff because of the extreme pressure of the sliding friction on the  hypoid gear teeth. Note it's these anti friction additives in GL5 that will render your gearbox synchro's near useless - so I use GL4 in the gearbox +1 GL4 Gearbox, GL5 Diff. Quote Link to post Share on other sites
stuart Posted October 21, 2020 Report Share Posted October 21, 2020 I wouldnt use GL5 in a diff. Stuart. Quote Link to post Share on other sites
DRD Posted October 21, 2020 Author Report Share Posted October 21, 2020 7 minutes ago, stuart said: I wouldnt use GL5 in a diff. Stuart. Some GL5 oils are supposedly OK with yellow metals. Quote Link to post Share on other sites
stuart Posted October 21, 2020 Report Share Posted October 21, 2020 1 hour ago, DRD said: Some GL5 oils are supposedly OK with yellow metals. "Some" is not specific enough to be used as good advice though. GL4 is perfectly adequate. Stuart. Quote Link to post Share on other sites
DRD Posted October 21, 2020 Author Report Share Posted October 21, 2020 7 minutes ago, stuart said: "Some" is not specific enough to be used as good advice though. GL4 is perfectly adequate. Stuart. Penrite? Dynalite? 80W/90 both claim to be OK. Quote Link to post Share on other sites
astontr6 Posted October 21, 2020 Report Share Posted October 21, 2020 3 minutes ago, stuart said: "Some" is not specific enough to be used as good advice though. GL4 is perfectly adequate. Stuart. About 5 years ago I spoke to Penrite & Castrol Technical Dept. and they both said the same thing that the early versions of EP did attack bronze metal but that was not the case anymore for the last 20 years. Penrite were very descriptive in Anglo Saxon saying that was a load of old F...... Balls now! Bruce. Quote Link to post Share on other sites
JohnC Posted October 21, 2020 Report Share Posted October 21, 2020 10 minutes ago, astontr6 said: Penrite were very descriptive in Anglo Saxon saying that was a load of old F...... Balls now! So were Penrite's Australian tech department when I asked the question nearly 20 years ago. Glad they're consistent Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 21, 2020 Report Share Posted October 21, 2020 2 hours ago, stuart said: "Some" is not specific enough to be used as good advice though. GL4 is perfectly adequate. Stuart. This issue burbles along around the world - I am old fashioned and stick with API GL-4 spec for both axle and gearbox with overdrive. https://bobistheoilguy.com/forums/threads/differential-oil-gl4.268674/ Quote Link to post Share on other sites
Phil Read Posted October 21, 2020 Report Share Posted October 21, 2020 Complicated isnt it. When I was in the trade back in the 60s and 70s it was EP90/140 or nowt. Now you have GL1-6 although I think 6 is not available. A little reseach shows that GL5 is ok is final drives but not in transmissions eg gearboxes. I still use a common or garden EP90 in my final drive, its cheap readily available and meets the manufacturers spec. Unless your a racer, doing donuts and wheel spins you should not need anything else. Quote Link to post Share on other sites
JochemsTR Posted October 22, 2020 Report Share Posted October 22, 2020 I apologize...I used and recommended GL5 for Diff. After this thread I contacted Liqui Moly direct and they recommended me: Hypoid-Gearbox Oil (GL4/5) TDL SAE 80W-90. The TDL Oil have the properties of GL4 (bronze metal) but also the pressure properties of GL5. Jochem Quote Link to post Share on other sites
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