Oil weight

Discussion in 'Mechanics Garage' started by gorillasnacks, Jun 5, 2018.

  1. gorillasnacks

    gorillasnacks New Member

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    Hey guys, just wanted to ask what oil weight you run in your fourth and fifth gen vfrs. I've asked several different people what they recommend, and everyone has different answers. I would like to know what you guys think.
     
  2. squirrelman

    squirrelman Member

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    look in your owner's or service manual rather than getting various opinions.
     
  3. gorillasnacks

    gorillasnacks New Member

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    Yes, I always go with what the manufacturer recommends, but these two bikes have had different weight oils in them from the previous owners and I just wanted to hear from people why they use something different from what's recommended. I haven't changed the oil yet in the fourth gen bike. The guy at my local honda dealership is telling me I should put one weight in it, and the previous owner used a different weight. I was thinking about keeping the same brand and weight in it that the previous owner used, just wanted hear what other people thought.
     
  4. squirrelman

    squirrelman Member

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    weight depends alot upon the temperatures you expect to ride in.

    if you have alot of miles on the bike and live in a hot climate, 20W-50 would be OK.
     
  5. gorillasnacks

    gorillasnacks New Member

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    Right on, the previous owner used 20w-50, but the bike only has 11k miles on it. It gets hot here in the summer for a month or two, but definitely not like south Florida or Texas.
     
  6. FJ12rydertoo

    FJ12rydertoo Member

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    IMO and from previous experience 20W-50 oil would probably be a bad oil to use in a hot climate,
    since it will run hotter than a 15W-40. I installed an oil temperature gauge in a 1980 Suzuki GS1000G.
    Since the GS is an air cooled engine I was wondering how hot the oil normally ran. I discovered that the
    20W-50 motor oil ran consistently higher temperatures than a 10W-40. That put me off the heavier weight
    oils permanently. Granted the GS1000G was a roller bearing crank engine versus the plain bearing crank
    VFR engine, but I still think the 20W-50 will run hotter. The VFR engine, IMO anyway, tends to run kind of
    hot, so I would do everything I could to keep the heat down.

    I just changed the oil in my '99 VFR yesterday and after much dithering went with Shell Rotella T-6 Synthetic
    15W-40. Before that I was running Castrol Syntec 5W-40, but it is no longer available as of several years ago.
     
  7. squirrelman

    squirrelman Member

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    any theories why that might be ?
     
  8. FJ12rydertoo

    FJ12rydertoo Member

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    The only thing I can think of, since I'm no engineer, is that the higher resistance to pumping/moving the oil,
    due to its higher viscosity, creates a bit more heat.

    But I honestly don't know, but it was a measurable change in temperatures and, in truth, it surprised me. I
    also figured that the higher weight oil would give better protection, but I hadn't anticipated the increase in
    heat. Go figure.
     
  9. NorcalBoy

    NorcalBoy Member

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    The weight of oil is approximately 6.8 pounds per gallon. You're welcome.
     
    TOE CUTTER and gorillasnacks like this.
  10. FJ12rydertoo

    FJ12rydertoo Member

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    I was speaking of viscosity, hence the use of the descriptive adjective "higher", rather than the literal weight
    which would require the use of the descriptive adjective "heavier".

    You're welcome.
     
  11. gorillasnacks

    gorillasnacks New Member

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    Bwahahahaha. I never thought about the weight of oil in that sense. Lol
     
  12. squirrelman

    squirrelman Member

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    i'm skeptical and think the testing conditions were too different for good comparison. plus, air-cooled vs. water-cooled may factor in.
     
    Last edited: Jun 6, 2018
  13. gorillasnacks

    gorillasnacks New Member

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    I broke down and consulted the service manual. Lol
    The recommended 10w-40 looks like it's made for cooler weather, the 20-50 is on the hot weather end of the chart. From what I've been researching I see it's made to handle higher engine temps. Especially in big v twin air cooled bikes. Since the 20-50 is on the chart for hot weather riding I think I'm going to stick with it. If it's on the chart, it's recommended right?
     

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  14. FJ12rydertoo

    FJ12rydertoo Member

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    The "testing" occurred when I changed from 20W-50 to 10W-40 and the average temps went down. I put nearly 30,000 miles on that bike in a bit less than 3 years, and changed oil every 3,000-4,ooo miles. That's when I was anal about changing oil. I was just telling you what I observed: average temps were higher with 20W-50 than with 10W-40. Just my observation, and putting it out there.

    It's pretty easy to do the same, use a remote meat probe if you don't want to install an oil temperature gauge. And check the oil temps periodically with both weights of oil. Be a pretty good experiment and I'd be curious to know the results. Just a thought.
     
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