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Transmission oil

  • Jim
    Jim
    4 months
    Gday everyone, looking for opinions on Penrite sae10w40 gear oil for 2012 Fatbob. Penrite recommend it for the transmission, although cannot find many comments of others on the net using it. Cheers 
    Screenshot_20250818_212842_Chrome.jpg
  • Retroman
    Retroman
    4 months
    I have been using this in the primary for a long time now. Penrite Pro Gear 75w85. On the shelf at Supercheap, easy.
    Wee motorcycle logo on the bottle.

    Transmission/ gearbox I have been using Redline Heavy Shock in my personal bike (hard to get by comparison)

    So I keep this now on the shelf for servicing mate's bikes.
    Penrite Pro Gear 80w140. Again easy to get, on the shelf at Supercheap.
    Don't let the naysayers say "too thick", HD started selling a "genuine" 80w140 synthetic gear oil a coupla years back.
    HD oil WAY more expensive than the Penrite oils, only downer is the Penrite come in 2.5 litre bottles, but have a super handy pouring spout.

    Penrite 75w85_3.jpg
    Penrite Pro gear 80w140.png
  • Jim
    Jim
    4 months
    Thanks retro man. Cheers 
  • tussuck
    tussuck
    4 months
    good calls in the oil... you would have more viscosity pissing in the tranny than going with 10w40 thats for sure.
  • tussuck
    tussuck
    4 months
    Does anyone sell a 20 container of engines oil thats compertitivly priced to the OEM Harley Oil....  I'm keen to stop buying chit from the orange country for a while.  Not look for an oil war.
  • tussuck
    tussuck
    4 months
    Thats a pretty good price tbh....  1/2 price when compared to the OEM dino stuff.  Free postage as well from some places.
  • wildchild
    wildchild
    4 days ago
    Quoting Retroman on 19 Aug 2025 05:52 AM

    I have been using this in the primary for a long time now. Penrite Pro Gear 75w85. On the shelf at Supercheap, easy.

    Wee motorcycle logo on the bottle.

    Transmission/ gearbox I have been using Redline Heavy Shock in my personal bike (hard to get by comparison)

    So I keep this now on the shelf for servicing mate's bikes.
    Penrite Pro Gear 80w140. Again easy to get, on the shelf at Supercheap.
    Don't let the naysayers say "too thick", HD started selling a "genuine" 80w140 synthetic gear oil a coupla years back.
    HD oil WAY more expensive than the Penrite oils, only downer is the Penrite come in 2.5 litre bottles, but have a super handy pouring spout.

    Penrite 75w85_3.jpg
    Penrite Pro gear 80w140.png
    I have been using Spectro 6 Speed Transmission and Spectro Primary oil in all my bikes Twin cam Softail and 110cc CVO Touring for well over 10 years.
    With availability only online from my location and not having any oil after a clutch cable replacement over the holidays now looking at an alternative that is readily available in my area. Penrite is available at all automotive stores which is why it may be good to go with for now and future oil changes.

    Looking at Pro Gear 80W140 for the Transmission, it is a GL5 rated oil but is it good for all metals in the 6-speed transmission?
    For the Primary, how do you find Pro Gear 75w85?

    Any reason for using Red Line over the Pro Gear 80w140 in your own bike?

  • Hilly
    Hilly
    4 days ago
    That is the thing, some oils are not so friendly to synchros, it is why I've changed what I use in my twin cam softail slim. Still penrite but synchro friendly stuff. 
  • Retroman
    Retroman
    4 days ago
    I have been using Redline Heavy shock in my Softails and Dynas since the 90's 5 speed days. Changed 2 yearly.

    Had it on the shelf and just kept using it in my own bikes(s), often had 2. Bought from a relatively local wholesaler back then.

    Been eBaying it the last few years if/when I spot it on special at Harold Performanceclub or another ebay reseller.

    When I am servicing for mates or contacts, Redline, well some of them baulk at the price, up to $45 per quart.

    Hence the Penrite 80w140 bought in 2.5 litres bottes in multiples of 2, 2 tubs = 5 services for me.
    Penrite 75w85 is fine for the primary.
    Again 2 bottles  =5 services
  • Uncle Ho
    Uncle Ho
    3 days ago
    Quoting Retroman on 04 Jan 2026 08:28 AMedited: 04 Jan 2026 12:05 PM

    I have been using Redline Heavy shock in my Softails and Dynas since the 90's 5 speed days. Changed 2 yearly.


    Had it on the shelf and just kept using it in my own bikes(s), often had 2. Bought from a relatively local wholesaler back then.

    Been eBaying it the last few years if/when I spot it on special at Harold Performanceclub or another ebay reseller.

    When I am servicing for mates or contacts, Redline, well some of them baulk at the price, up to $45 per quart.

    Hence the Penrite 80w140 bought in 2.5 litres bottes in multiples of 2, 2 tubs = 5 services for me.
    Penrite 75w85 is fine for the primary.
    Again 2 bottles  =5 services

    I was buying from Harold for my 2007 Street Bob as he is local. Been using HD oils for my 2022 Low Rider S, but will switch to Redline for the next service at 12K. I do oil every 4K and primary/transmission every 8K. 
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