Gearbox Oil

Discussion in 'Mech Tech' started by Skater 8, Jan 15, 2020.

  1. This oil on eBay is less than half the price of Castrol Translube, do folks think it will do the job?[​IMG]

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  2. John, generally speaking we should be avoiding anything exclusively GL 5 spec.

    GL 5 has corrosive effects on the synchroniser rings that assist with gear changes...Not a good look!
    As your proposed purchase is backwards compatible GL 4 spec it should be fine.
    The oil we use in all T3 gearbox rebuilds, including the syncro transmission and the front differential is:
    If you want an old school mineral oil at 80 weight as per factory recommendation then Smith and Allen also have this:
    I have the FS 75/90 front and rear in the syncro. It's available in smaller pack size and has the benefits of a synthetic blended weight which can make changes smoother, especially when it's a bit cold.
    Change the oil every 20k and you'll get a lot more value out of the gearbox. Oil is cheap at 13 quid or whatever it is for 5l, gearboxes less so.
    Gnasha, vinnyboy and Skater 8 like this.
  3. It will be fine, synthetic gear oils can meet GL5 spec without the addition of Sulphur/Phosphorus so are compatible with GL4 spec. Transaxles are a problem the diff needs an extreme pressure lubricant but the gearbox can run with normal oil some manual gearboxes just use engine oil or even ATF. EP90 is better for the diff but leads to gear selection problems so VW compromised on EP 8o. Modern multigrade gear oils offer the best of both worlds.
  4. Thanks both! With the savings I get from not buying Castrol Transaxle I can buy a decent bottle of malt whisky! Photo of drain plug to follow in due course.

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    Iain McAvoy likes this.
  5. @Skater 8 make sure you can get the filler plug out, before you drain the old oil out :thumbsup: Dont ask me how i know that !!!!
    Gnasha, JT1, Valveandy and 5 others like this.
  6. JT1



    Been using it since October 2018 and it has improved the gear change. noticeably. Mind you there were only 2 litres in it when the gearbox was drained so that may have something to do with the change quality:thinking:
    Link to the original thread
  7. There has been a recent thread on the Samba where for some GL-5 oils the effect is to make the synchromesh too slippery on some VW aircooled gearboxes so you lose second or third gear as it will just keep crunching, and the only way back was to replace parts in the gear box.

    As usual it doesnt happen to everybody, its probably happens to gearboxes that were about to fail anyway.

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