Final Drive Oil - GL4 or GL5?

Felters

Joined
Oct 5, 2012
Messages
1
Location
Hampshire - UK
Bike
ST1100
I've searched and read all the threads that were found - but am still confused.

GL4 or GL5? Or doesn't it matter?

I'm in the UK so the brands are different to the stuff in the US. I just need to understand the spec. The owners manual doesn't say anything on this.

Thanks
Mike
 
Felters said:
I've searched and read all the threads that were found - but am still confused.

GL4 or GL5? Or doesn't it matter?

I'm in the UK so the brands are different to the stuff in the US. I just need to understand the spec. The owners manual doesn't say anything on this.

Thanks
Mike
Click to expand...

The service manual says "hypoid gear oil, SAE 80W" No mention is made of GL4 or GL5 rating. FWIW, I replaced mine in around 1997 or 1998 with a synthetic gear oil that the owner of Maxima oils suggested should be good "for the life of the bike". Last year I decided that maybe it wouldn't kill me to change it again just in case. The bike had 90k miles or so on it since the previous change and there was no sign of metal shavings etc. when I changed it.
 
GL - 4 is a ISO - VG 150 grade. This to me is your winter grade.
GL - 5 is a ISO- VG 220 grade. This to me is your summer grade.
We use a mixture of the above over here so we can keep it in the differential all year round.
This is called 80W - 90. W stands for (winter)
I would use the GL - 5 if it is above 10 Celsius.
 
Felters said:
I've searched and read all the threads that were found - but am still confused.

GL4 or GL5? Or doesn't it matter?

I'm in the UK so the brands are different to the stuff in the US. I just need to understand the spec. The owners manual doesn't say anything on this.

Thanks
Mike
Click to expand...

Not quite as bad as a tire thread....lol. The synthetic replacement for any 80-90W conv. for the final drive is 75-140W. Has same 'cling' and other factors. An 80-90W in syn. has NOT the same cling and lubricating factors, and have seen two different final drives trash internal bearings on XS 11's cause of this mistake. Preference is up to you, but RoyalPurple is most preferred. Your final drive will also run cooler temps. Les heat = less friction.
 
GL4 vrs GL5 hypoid gear oil. GL5 hypoid gear oil has around 50% more sulfur/phosphorous additive (extreme pressure additive) than GL4. GL5 is superior in final drives. GL4 is superior in synchronized transmissions, especially those than use yellow metal synchronizes. The sulfur/phosphorous additive is corrosive to yellow metals. My '91 ST1100 manual calls for 80W hypoid gear oil. While GL4 will work in a final drive application, GL5 will be much better. Dino oil is usually 80W-90 and synthetic is 75W-90.

Here is a PDF file explaining the oils. Written for Corvair transaxles, but great explanation. http://www.widman.biz/uploads/Transaxle_oil.pdf
 
iride said:
I thought 80-90W is the weight of the gear oil, You know like motor oil, when its cool it will flow like a 80W and when its warm it will flow like a 90w gear oil???
140W is some pretty thick flowing gear oil...
Set me straight you guys,,,
Mike
Click to expand...

75W90 gear oil is about the same viscosity of 10W40 motor oil.
It's not apples to apples.
 
iride said:
I thought 80-90W is the weight of the gear oil, You know like motor oil, when its cool it will flow like a 80W and when its warm it will flow like a 90w gear oil???
140W is some pretty thick flowing gear oil...
Set me straight you guys,,,
Mike
Click to expand...

Not the case with the newer synthetic oils......more involved than just flow. Cling, pound-out and other factores come into play. Just for example: my F-350 diff. has a tag saying 75-140W ONLY. Now the internals, bearings and such haven't changed even though it's a yr.2000 truck. That diff. is the same as twenty yrs. ago. It's the lube that's changed. I'm just sayin' from experience, the ole' 80-90w diff. lube is still a good choice for these bike diffs.......BUT if you choose to use synthetic of your choice, use the 75-140w. That IS the equivalent. Like I stated, have seen two different final drives trash themselves out using equivalent weight rated synthetics. This was rolling LD on the slab, some 5,200miles on one trip for one of them. Don't know how to explain it any plainer without going into a super long scientific explanation, which this is intended to not be. Just plain and simple with results and examples to back it up. Going synthetic with gear lube WILL reduce the heat. Heat equals nothing more than friction, period. Reduced friction IS reduced wear, which reduces factory clearance changes. Just sayin be careful of your weight rating choices if going synthetic. They are NOT the equivalent, no matter what the salesmen or container say. BTW, 75-140w synthetic pours same as 1040w motor oil, if that matters to you.
 
dwalby said:
The service manual says "hypoid gear oil, SAE 80W" No mention is made of GL4 or GL5 rating
Click to expand...

I'm following you around Dwalby LOL, like everything with this bike I find confusing answers, I got 80 w 90 gear oil today but its GL4, is this ok to use in the final drive or should I look for GL5?
Would it be ok if the GL4 was used and then you went to GL5? would the final drive need to be flushed out?
Can anyone enlighten me? thanks
 
broc11 said:
I'm following you around Dwalby LOL, like everything with this bike I find confusing answers, I got 80 w 90 gear oil today but its GL4, is this ok to use in the final drive or should I look for GL5?
Would it be ok if the GL4 was used and then you went to GL5? would the final drive need to be flushed out?
Can anyone enlighten me? thanks
Click to expand...

from a quick web search the consensus seems to be that GL5 is better in final drives because of more extreme pressure additives. The few gear oils I found with a quick search were all GL5, they appear to be pretty easy to find. I suspect in a low power application like the ST the difference between GL4/GL5 is probably not all that important, and is probably why Honda doesn't specify one or the other. So if you really can't locate some GL5 easily, the GL4 should be fine for the application. And the base oil is similar, so you wouldn't need to do any flushing going from one to the other.
 
Thanks Dwalby,I suppose as you say it wont make a big difference either way,there was a fair amount of grey goup on the magnetic drain plug,though the old oil looked fairly good so it was probably changed before at some point.
 
BuddingGeezer said:
...GL5 is superior in final drives. GL4 is superior in synchronized transmissions...
Click to expand...
+1... Definitely GL5 for the hypoid gears of the final drive. (but never put a GL5 into a manual car gearbox, syncing will fail... its GL4 there)
 
Jim Van said:
I would use either Amsoil Severe Gear 75W-90 or Synthetic 80W-90 Gear Lube. I think 75W-140 isn't really necessary, but won't hurt either. http://www.amsoil.com/shop/by-product/gear-lube/
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I see from Amsoil's site that the recommended change interval is 100k miles. That's pretty much consistent with what I was told by the Maxima guy many years ago. I know a lot of folks here change the final drive oil at much shorter intervals, which is probably overkill. But, given the fact that the smallest container has enough oil for several changes, no sense in leaving it sitting on the shelf forever either.
 
dwalby said:
I see from Amsoil's site that the recommended change interval is 100k miles. That's pretty much consistent with what I was told by the Maxima guy many years ago. I know a lot of folks here change the final drive oil at much shorter intervals, which is probably overkill. But, given the fact that the smallest container has enough oil for several changes, no sense in leaving it sitting on the shelf forever either.
Click to expand...

Me too. It doesn't take that long and only requires about 5 oz. , like you said , and I'm a preventative maintenance freak, anyway.
 
dwalby said:
I see from Amsoil's site that the recommended change interval is 100k miles. That's pretty much consistent with what I was told by the Maxima guy many years ago. I know a lot of folks here change the final drive oil at much shorter intervals, which is probably overkill. But, given the fact that the smallest container has enough oil for several changes, no sense in leaving it sitting on the shelf forever either.
Click to expand...

Nevar!!! Change it at least once a year. The rear diff vent is far more exposed than autos, and autos have far more volume. You may find the bike's oil is a bit milky, which means moisture got in through the vent. If you ride longer rides where the operating temperature is sustained for a couple of hours, moisture may not be a problem. Commuting short distances may not drive it out. Honda says inspect every 8k miles and replace at 24k. Yamaha says similar, replace at 16k miles or every 2 years. I usually find I don't like the appearance after one year, so change it every year.

I know several who change it every oil change, which to me is over the top and unnecessary.
 
Well a litre costs 8 euros so it isn't hard to keep it changed,it only takes about 130ml, its a lot less messy than keeping the chain on my vfr oiled anyway.
 
RaYzerman said:
Nevar!!! Change it at least once a year. The rear diff vent is far more exposed than autos, and autos have far more volume. You may find the bike's oil is a bit milky, which means moisture got in through the vent. If you ride longer rides where the operating temperature is sustained for a couple of hours, moisture may not be a problem. Commuting short distances may not drive it out. Honda says inspect every 8k miles and replace at 24k. Yamaha says similar, replace at 16k miles or every 2 years. I usually find I don't like the appearance after one year, so change it every year.

I know several who change it every oil change, which to me is over the top and unnecessary.
Click to expand...

Unlike engine oil, which can get hot enough to boil away traces of water, I don't think the final drive ever gets anywhere near that hot. So I think if you get moisture inside you're stuck with it until you drain it regardless of how you ride. That being said, those of us who live in dry climates don't really have to be concerned with that. Based on the advice of the Maxima guy I changed mine sometime around 1999 and never changed it again until about 2011, as my yearly mileage had dropped substantially during that period. The old oil looked OK when I drained it, it probably had about 60-70k miles on it.
 
I decided to change mine a while back....I had ridden the bike 15K and was unsure what had been done prior...
So I poured some Mercruiser 80-140 into it, figuring that the folk at Mercury would want some pretty substantial oil in the final drive.
Have fun!
 
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