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Are car and motorcycle oils similar?

Discussion in 'Technical and Troubleshooting Torque' started by Mouth, Feb 20, 2016.

  1. unnamed (1).
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  2. I know of a many motorcyclists who swear by Shell Rotella which is really aimed at diesels.
    Rotella info
  3. #3 GreyBM, Feb 20, 2016
    Last edited: Feb 20, 2016
    Actually Mouth I think what you have answered is why they should be different. The question of how they are different remains a secret because the companies concerned won't tell us. They often won't even confirm that they are different.

    Some years back a British motorcycle magazine did some testing on motorcycle and car oils and they struggled to detect significant differences. One of the things they did test for was friction modifiers given the common belief that car oils contained them and motorcycle oils didn't. What they found was that most m/c oils contained them and though this generally was at a lower level than in car oils, there were still some m/c oils which had a higher of friction modifiers than some car oils.

    The testing was not conclusive as a couple of the tests were very expensive so only a couple of oils were put through those tests, However again for those that were tested no significant difference was found. Consequently the results left a nagging doubt that motorcyclists were simply paying a premium for a product on the basis of spurious claims that the products benefitted bikes (Yes, I know it is difficult to believe that big companies would mislead consumers in the interests of profits) but the magazine wouldn't go as far as to say that as their tests were not exhaustive.

    When asked to comment, the oil companies insisted that their m/c oils were specifically designed for and beneficial to bikes but refused to say how or what the differences were.

    One obvious difference that we can identify is that m/c oils costs significantly more than oil for their four wheeled cousins.

    Meanwhile there is the Oil thread somewhere in Netrider (cbf looking or posting a link) which shows that lots of Netriders are buying relatively cheap diesel oil and successfully using it in their bikes without any problems. Warning it is a bloody long thread and most people will fall asleep well before reading it all.

    - I am not convinced their is an incorrect reply.

    And don't get me started on chain lube.
  4. Dave, how often do you change the Oil in the Cat?

  5. Some years ago I owned a Suzuki T250 2stroke. I put Castrol GTX in the gearbox. I had to flush it all out and wash the clutch plates with diesel fuel to get rid of it as it made the clutch slip. Clutch problems don't always seem to occur with many riders and things may be different these days but I ensure that the oil I use has the specs that the bikes manual states. Rotella Diesel oil does however it is common in the USA but not here. I don't go buying fancy expensive oils as I don't race my bikes. As long as the oil meets manufacturers recommendations it is good enough and the cheaper the better.
  6. One of us is buying the wrong oil. I pay more per litre for my car oil than the bike, use more of it and change it just as frequently.
  7. Yeah there was, I'd written that a lot of front wheel drive cars shared engine and gearbox oil too, but upon reflection, that's the exception, not the norm.
  8. Cat D8 dozer, every 350 operating hours ;-)
  9. Having long ago gotten sick of paying way over the odds for motorcycle oil that is no better..........

    if you read the product info, each is specifically identified as suitable for motorcycle ie. wet clutch use.
    for everyday use FULL SYNTHETIC 10W-40
    for more spirited use RACING 10W-40 (100% PAO ESTER)
    for use when it must have the word motorcycle on the front of the label MC-4 FULL SYNTHETIC 10W-40

    All available at your local supercrap or similar store, sometimes even priced lower when on special .....
    • Informative Informative x 1
  10. #10 kneedragon, Feb 21, 2016
    Last edited: Feb 21, 2016
    Some years ago ('86) I left the fuel tap on, on a GSX11 and flooded the engine over the weekend. I thought it wouldn't crank over because the battery was flat, but that wasn't the problem... I drained it, and then got fresh oil, and then had a hunt around for some any-old-oil to put in there and run it once, for about 10 seconds, and flush with. I found about 5 or 6 oil containers that still had something left and managed to put about 2l together (should have been 3.4 litres) and figured that was good enough. One of the oils I put in there was friction modified. (No, I forget which one...) That clutch slipped from that day on, and after about a thousand km of messing about with it, I changed the clutch, both pressure and friction. That fixed it... I won't be doing that again...

    Mobile 1 is not the cheapest oil. I have not used it myself but I have spoken to several people who have. It is a very high quality oil (fully synthetic) and it does not seem to do any harm to clutches or stuff. My objection (from memory) was that it cost about $100 for a 5 litre pack that should cost about $20 ~ 30.