hot-growler Posted September 6, 2020 Report Share Posted September 6, 2020 Hi, have gearbox out to do an engine rebuild, and am wondering what oil to use in the gearbox. is an a type with o/d on 2,3 and 4. currently have had ep 90 and not had any issues with overdrive, but heard 20W50 as an option. Would like some advice on pros and cons of both, Thanks Steve Quote Link to post Share on other sites
RogerH Posted September 6, 2020 Report Share Posted September 6, 2020 Hi Steve, if you use an EP oil make sure that it is to GL4 spec. Many are GL5 and this is not good at all. Regards 20/50 - this is basically a 40 grade oil. I would recommend Penrite GB40 - it is designed for gearboxes. If you try a 20/50 engine oil you may the OD stop or becomes sluggish due to frothing. Engine oil often has detergent in it. Roger Quote Link to post Share on other sites
astontr6 Posted September 6, 2020 Report Share Posted September 6, 2020 5 minutes ago, RogerH said: Hi Steve, if you use an EP oil make sure that it is to GL4 spec. Many are GL5 and this is not good at all. Regards 20/50 - this is basically a 40 grade oil. I would recommend Penrite GB40 - it is designed for gearboxes. If you try a 20/50 engine oil you may the OD stop or becomes sluggish due to frothing. Engine oil often has detergent in it. Roger We had a member use ordinary 20/50 in his gearbox against my advice and it gummed up the oil ways in his O/D with a white sludge because the teeth on the cogs were breaking down the oil. Gearbox had to come out and taken to ORS for rebuild at a cost of £1200 + Labour to take out and refit as they found other things wrong like the layshaft and needle rollers. He went back to EP oil 80/90 grade GL4 made by Castrol. No problems since. Bruce. Quote Link to post Share on other sites
Mike C Posted September 6, 2020 Report Share Posted September 6, 2020 9 hours ago, RogerH said: Hi Steve, if you use an EP oil make sure that it is to GL4 spec. Many are GL5 and this is not good at all. Regards 20/50 - this is basically a 40 grade oil. I would recommend Penrite GB40 - it is designed for gearboxes. If you try a 20/50 engine oil you may the OD stop or becomes sluggish due to frothing. Engine oil often has detergent in it. Roger A repair shop filled my gearbox/OD with GL5 oil by mistake. The GL5 boundary layer additives caused it to jump out of gear on the overrun and the synchro's to grate. Flushed it out with 2 changes of GL4 and all is fine again. Quote Link to post Share on other sites
hot-growler Posted September 7, 2020 Author Report Share Posted September 7, 2020 Thanks, GL4 it is then. Have some gear oil on the shelf, will check the spec before using it. Excellent forum as always. Steve Quote Link to post Share on other sites
SpitFireSIX Posted September 7, 2020 Report Share Posted September 7, 2020 On 9/6/2020 at 2:31 PM, RogerH said: Hi Steve, if you use an EP oil make sure that it is to GL4 spec. Many are GL5 and this is not good at all. Regards 20/50 - this is basically a 40 grade oil. I would recommend Penrite GB40 - it is designed for gearboxes. If you try a 20/50 engine oil you may the OD stop or becomes sluggish due to frothing. Engine oil often has detergent in it. Roger Hi Roger, Not all GL5 gear box oils are bad. Quote Link to post Share on other sites
Nigel Triumph Posted September 7, 2020 Report Share Posted September 7, 2020 Just now, SpitFireSIX said: Hi Roger, Not all GL5 gear box oils are bad. But I wouldn't want to take the chance. EP90 GL4 every time for my gearboxes. Nigel Quote Link to post Share on other sites
RogerH Posted September 7, 2020 Report Share Posted September 7, 2020 19 minutes ago, SpitFireSIX said: Hi Roger, Not all GL5 gear box oils are bad. what is that based on. I appreciate that modern oils may be better than decades ago - but!!! Roger Quote Link to post Share on other sites
SpitFireSIX Posted September 7, 2020 Report Share Posted September 7, 2020 Just now, RogerH said: what is that based on. I appreciate that modern oils may be better than decades ago - but!!! Roger There are GL5 oils out there that are fine in the TR gearboxes that were originally speced for GL4. There are GL5 oils that are bad for the gearboxes. Check the info on the container. Quote Link to post Share on other sites
ntc Posted September 7, 2020 Report Share Posted September 7, 2020 This old topic again, I have been using Mobil 1 20’50 for over twenty years as recommended by the legend Roy Talbot and never had any problems Quote Link to post Share on other sites
Mike C Posted September 7, 2020 Report Share Posted September 7, 2020 2 hours ago, SpitFireSIX said: There are GL5 oils out there that are fine in the TR gearboxes that were originally speced for GL4. There are GL5 oils that are bad for the gearboxes. Check the info on the container. What do you look for? The lack of boundary friction additives? Quote Link to post Share on other sites
astontr6 Posted September 8, 2020 Report Share Posted September 8, 2020 12 hours ago, ntc said: This old topic again, I have been using Mobil 1 20’50 for over twenty years as recommended by the legend Roy Talbot and never had any problems Your Mobil oil may be suitable for use in Minis that is why you have not had any trouble as it has Hypoy added to cope with the Transverse Gear Box & Hypoy cut gear teeth? This enabled BL to produce the original Mini Engine Layout using Castrol oil which was developed for this application with Hypoy additives. Bruce. Quote Link to post Share on other sites
SpitFireSIX Posted September 9, 2020 Report Share Posted September 9, 2020 (edited) On 9/8/2020 at 12:02 AM, Mike C said: What do you look for? The lack of boundary friction additives? It will say suitable for synchromesh gearboxes. It If not: Don't use it! Edited September 10, 2020 by SpitFireSIX edit Quote Link to post Share on other sites
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