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Type of oil for SV transmission 4speed man
- Thread starter Tai2002
- Start date
puff4
Platinum Level Sponsor
The factory recommended standard motor oil - so did BMC with your Sprite - and it's the best thing to use. I use a non-detergent 30w oil and it works just fine.
Detergent oils keep debris (bearing bits, gear chips, etc.) suspended in the oil so that an oil filter can pick them up and clean them from the oil. However, in a gearbox you don't have a filter, so these bits, if left in suspension, would cause further damage to the gears and bearings. Instead, you want all that rubbish to settle out and form a sludge in the bottom of the gearbox (yeah, really!) So... use a non-detergent oil in the gearbox. If the sludge thing bothers you, then every few years you can flush out the gearbox with cleaning solvent, if you're particularly fastidious.
If you have trouble finding non-detergent oil, look for oil used for lawn mowers and other non-filtered devices - that's the stuff.
Nickodell
Donation Time
Hi, Kevin. Reminds me of my first car, a 1939 Austin. It had no oil filter - well it did have some metal mesh on the oil pump to stop chunks of junk circulating - and of course was designed and built decades before detergent oils appeared. One day I dropped the pan for some reason and was amazed to see a good 3/4" of solid gunk in the bottom. As you say, with non-detergent oil it just settled out where the oil pump couldn't pick it up and did no harm.
However, I don't think your gearbox analogy is valid. Most of the crap circulating in engine oil is products of combustion, mainly carbon, water and acids. This doesn't apply in a gearbox so it needs no filter. Any bits of metal from gears would settle to the bottom through gravity, which is why topping up gearbox oil is not enough; it should be drained periodically not because it degrades like engine oil, but to remove these particles.
IMHO, it doesn't matter whether you use detergent or non-detergent oil in a non-OD box. With an OD, it may be a different matter.
However, I don't think your gearbox analogy is valid. Most of the crap circulating in engine oil is products of combustion, mainly carbon, water and acids. This doesn't apply in a gearbox so it needs no filter. Any bits of metal from gears would settle to the bottom through gravity, which is why topping up gearbox oil is not enough; it should be drained periodically not because it degrades like engine oil, but to remove these particles.
IMHO, it doesn't matter whether you use detergent or non-detergent oil in a non-OD box. With an OD, it may be a different matter.
puff4
Platinum Level Sponsor
Those particles can be *very* fine, Nick - finer than baby powder - and they will stay suspended for quite a while if you use detergent oil. Having rebuilt a great many gearboxes and seen the amount of swarf in the bottoms of the cases, I do think it matters very much whether you use detergent or non-detergent - I certainly would not want that stuff floating around in my bearings.
As to draining, yes, that can help a bit, but frankly most of the rubbish sticks to the bottom like glue and just draining won't pull out much junk... that's why I say to flush it with light fluid (kerosene will work) but not to drive it until it's filled with new oil and it's had plenty of time to settle again.
As to draining, yes, that can help a bit, but frankly most of the rubbish sticks to the bottom like glue and just draining won't pull out much junk... that's why I say to flush it with light fluid (kerosene will work) but not to drive it until it's filled with new oil and it's had plenty of time to settle again.
65beam
Donation Time
oil
keep in mind that the non detergent oils of today are blended with a different base stock,additives, etc. there is quite a difference between todays oils and 50 years ago. many of the less expensive oils sold today are blended using naphthenic base oils instead of paraffinic base oils. the napthenic oils don't come close to the lubricating properties of paraffinic oils. i use a straight 30 from one of the majors and have no problems. using a 10/30 wouldn't make a difference either since a 10/30 is a 30 with the properties of a 10 at cold temps. just don't use a conventional gear oil since the syncros will wear out fast. it would be interesting to send a sample of a non detergent oil from 50 years ago to a lab to see if it was a straight mineral oil or what additives were actually in it. the detergent is there to inhibit deposit formation which doesn't mean those deposits would go to the bottom and wouldn't be elsewhere in the transmission.
keep in mind that the non detergent oils of today are blended with a different base stock,additives, etc. there is quite a difference between todays oils and 50 years ago. many of the less expensive oils sold today are blended using naphthenic base oils instead of paraffinic base oils. the napthenic oils don't come close to the lubricating properties of paraffinic oils. i use a straight 30 from one of the majors and have no problems. using a 10/30 wouldn't make a difference either since a 10/30 is a 30 with the properties of a 10 at cold temps. just don't use a conventional gear oil since the syncros will wear out fast. it would be interesting to send a sample of a non detergent oil from 50 years ago to a lab to see if it was a straight mineral oil or what additives were actually in it. the detergent is there to inhibit deposit formation which doesn't mean those deposits would go to the bottom and wouldn't be elsewhere in the transmission.
Nickodell
Donation Time
Hmm. I'm still not convinced. I remember the dire warnings when Alex Issigonis turned the engine sideways and put the gearbox in the same sump. "Aaagh. You can't treat transmission gears like engines!" Issigonis didn't know that and just went ahead, starting the biggest revolution (no pun intended) in automotive engineering since the self-starter.
Talking of non-detergent oils reminds me of my earliest motoring in the early 50s. Firstly, you had to change the oil after running in (Brit. for breaking in) a new engine for 500 miles. You had to drive at about 30mph, with the occasional very short burst to 40, for that 500 miles, with lots of use of gears to prevent the engine lugging at low rpms. You had a notice in the rear window apologizing for holding everyone up: RUNNING IN. PLEASE PASS.
Then out with the oil, while hot. In with "flushing oil" (high detergent) that was used only for this purpose. Warm the engine up for no more than five minutes, then drain all that out, too. Then in with the new oil. Then repeat the process every 3,000 miles. In summer you used SAE 30 [NOT WEIGHT!
], and in winter SAE 20. As the engine wore, these went to SAE 40 and 30, and in the end 50 and 40.
Talking of non-detergent oils reminds me of my earliest motoring in the early 50s. Firstly, you had to change the oil after running in (Brit. for breaking in) a new engine for 500 miles. You had to drive at about 30mph, with the occasional very short burst to 40, for that 500 miles, with lots of use of gears to prevent the engine lugging at low rpms. You had a notice in the rear window apologizing for holding everyone up: RUNNING IN. PLEASE PASS.
Then out with the oil, while hot. In with "flushing oil" (high detergent) that was used only for this purpose. Warm the engine up for no more than five minutes, then drain all that out, too. Then in with the new oil. Then repeat the process every 3,000 miles. In summer you used SAE 30 [NOT WEIGHT!
], and in winter SAE 20. As the engine wore, these went to SAE 40 and 30, and in the end 50 and 40.
sunbeamowner
Bronze Level Sponsor
I use Penrite 30 for my series 1V gearbox/Overdrive. I was told that some modern oils have phospherus in them that can corrode some of the bronze parts in older gearboxes.
http://www.penriteoil.com.au/pis_pdfs/Gear Box 30 and 40 JAN 2011.pdf
Since I have been using Penrite I have found the gear changes are a bit smoother and a lot less 'snatching' going on.
http://www.penriteoil.com.au/pis_pdfs/Gear Box 30 and 40 JAN 2011.pdf
Since I have been using Penrite I have found the gear changes are a bit smoother and a lot less 'snatching' going on.