Classic cars forum & vehicle restoration.
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jiminox
Joined: 12 Dec 2011 Posts: 5
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Posted: Sun Dec 18, 2011 10:27 pm Post subject: humber hawk gearbox oil |
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Hi can anyone tell me where i can get 20w/20 oil, or something equivelent please. cheers jim. |
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richardlw
Joined: 08 Jun 2009 Posts: 138
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jiminox
Joined: 12 Dec 2011 Posts: 5
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Posted: Sat Dec 24, 2011 9:54 pm Post subject: |
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thanks richard |
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welshrover
Joined: 09 Aug 2011 Posts: 326
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Posted: Wed Sep 19, 2012 12:08 pm Post subject: |
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id put 20/50 engine oil in it. the rootes gearbox has small oilways. too small for gear oil ,all the rootes gearboxes are the same minx,gazelle etc
all the manuals say 20/50 and not!!!!!! gearoil
Last edited by welshrover on Wed Sep 19, 2012 10:53 pm; edited 1 time in total |
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richardlw
Joined: 08 Jun 2009 Posts: 138
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welshrover
Joined: 09 Aug 2011 Posts: 326
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Posted: Wed Sep 19, 2012 10:53 pm Post subject: |
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gear oil damages the syncrho hubs. there is some sort of reaction with the type of metal used in the hubs and the gear oil .thats what the rootes original factory manual says as well as the oil holes , |
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richardlw
Joined: 08 Jun 2009 Posts: 138
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Posted: Thu Sep 20, 2012 12:06 am Post subject: |
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That would be the true reason, not the viscosity. Although the difference is less than it was. About 15-20 years ago the oil producers started using buffered sulfur/phos compounds that are not corrosive. But, they wear the teeth off the sychncronizers if used in high enough concentrations. That is why you don't ever want to put GL-5 in transmissions, only GL-4.
But you can also consider that Diesel engine oil in general meets the GL-4 EP requirements, so that is why you can use it in the transmission. _________________ Richard's Cars - NEW **
Motor oil for Flat Tappet Engines
Transmission oil |
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exbmc
Joined: 18 Jun 2009 Posts: 236 Location: Derby East Midlands
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Posted: Thu Sep 20, 2012 4:21 pm Post subject: gearbox oil |
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It would be worth checking if one of the smaller oil companies, like Millers, Smith and Allan, or Morris's, have a 20w/20 oil in their classic ranges. What richardlw is saying is correct regarding viscosity, but i think you feel uneasy about using gear oil? It's not a common blend, in fact the only 20w/20 i recall using, was a Shell Rotella or BP for diesels. Some of the BMC light truck engines, had 20w/20 specified in the 60's. |
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Farmer John
Joined: 18 Feb 2010 Posts: 181 Location: Manawatu NZ
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Posted: Sun Sep 23, 2012 11:13 pm Post subject: gearbox oil |
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Hi Jim. The proper oil for your vehicle is that which the manufacturer recommends. That recommendation might have unfamiliar and unusual codes or letters and numbers to define the correct oil, but any oil you buy should have a spec sheet available from which you can match up the rating.
Some of those terms might have changed and that is where you will need someone who can translate for you. Maybe Richard can do that?
Richard had stated in your original thread that engine oils and transmission (industrial) oils have different rating systems, typically 212 deg F for one and 100 deg F for the other. That is because they are different oils, treat them as such.
The question of erosion of bronze synchro rings and thrust washers should also be answered from the spec sheet by reactivity with copper. Should not be a problem except for GL5.
Firms who supply oil to heavy vehicle and heavy industry are a good source for information and oil. Cummins, Caterpilar and the like are very specific on lubricants so the firms who supply them have to be right up to speed and have access to the best info. Unfortunately there are not so many of those firms around, but if you wander in with the manual or just the specs they will help.
Jim, if you put the right oil in the box you have eliminated one possible cause from your list.
John |
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richardlw
Joined: 08 Jun 2009 Posts: 138
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Posted: Mon Sep 24, 2012 2:38 pm Post subject: |
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Let's go back to square ONE for a minute. The first thing I would do is verify that the the manual or spec you have is correct. There are a lot of misprints out there. Check with someone who has the same transmission in a different vehicle. Is is 20W-20 or 20W-50? There is a big difference.
Most SAE 20W-20 oils on the market would give you an oil that is approx. between 60 and 70 cSt at 40˚C and 8 to 9 cSt at 100˚C (from common spec sheets).
SAE 20W-50 would give you approx. 150 to 160 cSt at 40˚C and 18 to 19 cSt at 100˚C.
Once you have determined that, it is easy to put a good product in it. I will assume it has brass, so I will only mention products that are compatible and won't induce wear.
If it really says 20W-50, use a diesel formula 20W-50. that will give you about 48 lbs on the Timken EP test, passing GL-4 requirements without any Sulfur/phos. Just ZDDP. This is what Isuzu uses in the Trooper, Rodeo, and pickups.
If it is 20W-20, come companies sell it, and it should be CI-4 or CJ-4, which will be harder to find. But you have other choices.
Our objective is to find something that doesn't thicken up to more than about 60 to 70 cSt at 40˚C and maintains at least 5.6 (but I'd prefer 7) to 9 cSt or so at 100˚C.
-- That could be the 75W-80 gear oil that I mentioned originally, normally available in GL-3 or GL-4. That would probably be around 40 to 45 at 40˚C and 7.5 at 100˚C.
-- Another choice would be a Synchromesh fluid (GM, Pennzoil, Quaker State, etc.) that would give you about 40 to 50 cSt at 40˚C and only thin down to 9 to 10 cSt at 100˚C. These are specifically designed for brass sychronizers.
-- Another choice would be SAE 5W-30 diesel formulation (CI-4, CJ-4) motor oil. Again, it would be giving you the 48 or so lbs on the Timken (Falex) test, and would give you about 60 cSt at 40˚C and about 10 cSt at 100˚C.
None of these oils will hurt the synchronizers. All will protect the gears, bearings, etc. (actually more important in viscosity than the passageways are the needle bearings that are present in many transmissions). _________________ Richard's Cars - NEW **
Motor oil for Flat Tappet Engines
Transmission oil |
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