Gear oils

[Robbie693]

Hello,

I know gear oils have been covered ad-infinitum in the past but I can't find anything that answers this specifically so..

I notice that Halfords no longer sell EP90 gear oil and that all they stock is 80w90 in both GL4 and GL5 flavours. Question is, do I need to find some EP90 or is this multigrade(?) stuff ok?

This is for the trunnions by the way (sorry - yet another post for the archive searcher of 'oil' and 'Trunnions'!)

Cheers

Robbie

[rocket]

Hi,

I have used 80w90 for a few years without problems.

Cheers,

Ian.

[gordont]

I posted a similar question for my S2 elan and for those using oil (as opposed to grease) GL4 seemed to be deemed suitable and readily available.

[kstrutt11]

Someone more knowlegeable may be able to comment but I remember reading somewhere that some GL5 oils contain substances which can attack bronze in older gearboxes.

[Robbie693]

Thanks chaps,

My concerns over the multigrade oil are based on my understanding that, for example, 80w90 means that, when cold, the oil act as a 80 weight oil until warm whan it acts as a 90 weight. If I have this correct then, as the trunnions don't get hot, with the 80w90 the oil won't be the correct grade. If this doesn't matter then why does the workshop manual specify EP90 and not either EP80 or 90?

I understand that GL5, with it's higher sulphur levels is bad for brass components and that GL4 should be used but surely the grade (viscosity?) of the oil is important too..?

Am I over analysing this?

Cheers

Robbie

[69S4]

If I have this correct then, as the trunnions don't get hot, with the 80w90 the oil won't be the correct grade. If this doesn't matter then why does the workshop manual specify EP90 and not either EP80 or 90?

Robbie

The usual argument is oil vs grease, so I wonder if the difference between 80 and 90 is significant when grease must be something like 1000.

[RichC]

that reminds me ... i'd like to oil my trunnions but don't know how i'd get it in!
can you get oilcans with the grease nipple fitment ?
or do you put the oil in a regular grease gun ( I'm thinking it might p.ss out everywhere...)
maybe remove the grease nipple?
or use a regular can with a tight fitting piece of rubber hose fitted over the grease nipple .... would that work?
RichC

[alexblack13]

Probably not Rich. More likely to need a bit more pressure than a std oil can can provide.

Most good quality grease guns will also do ok with an 80/90 oil. Try it and see. Make sure nipples are clean and fire a few strokes in until it comes out the top rubber seal.

I prefer liquid grease in mine...

Alex..

[Esprit2]

My concerns over the multigrade oil are based on my understanding that, for example, 80w90 means that, when cold, the oil act as a 80 weight oil until warm whan it acts as a 90 weight. If I have this correct then, as the trunnions don't get hot, with the 80w90 the oil won't be the correct grade. If this doesn't matter then why does the workshop manual specify EP90 and not either EP80 or 90?

Robbie,
All oils change viscosity as their temperature changes. How dramatically they change per unit of temperature change is called Viscosity Index. An oil that changes viscosity a lot has a low VI, and one that doesn't change much has a high VI.

All oils have only one viscosity characteristic, but it's measured at two different temperatures. When measured cold (frigid cold), the viscosity has a W suffix, and when measured hot, the viscosity is just a number. So 80W-90 means 80 when cold and 90 when hot.

Note that the xxW and xx viscosity scales are totally different, and that confuses many people. The thinnest W-grade is thicker than the thickest non-W grade, by a lot. A 90 weight oil when hot does not be come a 80 wt oil when cold, it becomes a xxW oil... a very different animal. It would have been more clear if two totally different scales had been used, like NN-90.

Straight weight gear oils have such low VIs that they basically gell-up and refuse to flow before chilling down to the standard measuring temperature. They won't flow in the laboratory test equipment, and they're pretty pasty and useless as a lubricant on the job as well. Since they can't be measured, they're not given the W rating. Or if they did, it would be like goopW80 verses solidW90.

An oil with a high enough VI to still be measurable and usefully fluid at the cold test temperature gets a W rating. You want the lubricant in your trunnions to remain fluid at cold temperatures, so an 80W-90 is much better in the cold than either an 80 or a 90, but an 80W-90 and a 90 are basically equivalent at normal operating conditions.

I understand that GL5, with it's higher sulphur levels is bad for brass components and that GL4 should be used but surely the grade (viscosity?) of the oil is important too..?

It was pretty normal for old GL5 gear oils to contain sulfur compounds that could be corrosive to brass/ bronze synchros, and some modern GL5's still contain them. However, there are now many GL5 gear oils that use other EP additives and are totally compatible with copper alloys. Read the labels or search the web, and you can find GL5 gear oils that would be perfectly acceptable for use in the trunnions. Actually, the GL5's EP and anti-wear characteristics would be advantageous for trunnions. It was only the corrosive nature of early GL5s that kept them from being recommended for use in trunnions in the first place.

Am I over analysing this?

Yes.

Regards,
Tim Engel
Lotus Owners Oftha North

[Esprit2]

can you get oilcans with the grease nipple fitment ?
or do you put the oil in a regular grease gun

Rich,
There are oil guns, and then there are oil guns. The typical little oil squirter found in most garages probably won't suffice, but an industrial oil gun will. I don't have the URL handy, but there's a company selling such an oil gun with the tip replaced by a length of hose and a grease tip specifically for oiling trunnions.

Either way, don't remove the grease nipple (zerk). You need a little pressure to force the oil fully into the trunnion's running clearances. If whatever you use can't muster the pressure required to get past the nipple, it probably doesn't have sufficient pressure to ensure proper oiling. Just use a grease gun or a proper oil gun on steroids.

Regars,
Tim Engel
Lotus Owners Oftha North

[alexblack13]

http://cgi.ebay.co.uk/WANNER-315-GREASE ... 56432ed11f

Try one of these. They don't leak oil at all. I fitted mine with a flexi rubber delivery (HP) hose and connector. Paid about ?7.00 for it and its about the best you can buy.. Swiss made & single hand operation.

Fill it with KLUBER liquid grease. Again the best you can get. You will not wear out trunnions at all then.

Alex B.....

[elan_fan]

elan-f14/modified-plessol-grease-gun-make-very-good-oil-gun-t22215.html

[Robbie693]

Tim,

You're a star - that's exactly the answer I was looking for. Thanks very much

Am I over analysing this?


Yes.

Regards,
Tim Engel
Lotus Owners Oftha North

Thought so!

Cheers

Robbie

[kstrutt11]

I found EP oil was a bit too fluid for trunions, I have been using semi fluid grease intended for the front swivels on Landrovers, this seems to work a treat and goes in easily with a normal greese gun.

kevin

[RichC]

good tips !
thanks folks
RichC