Interesting observation.

Discussion in 'General Harley Davidson Topic' started by horizonchaser, Jul 17, 2011.

  1. horizonchaser

    horizonchaser Senior Member Contributor

    Today I rode with some friends. When we stopped for breakfast one of the guys has and '08 Ultra has a digital oil temperature dipstick like myself. I have an '03 Ultra. We both checked the temperature of out oils. His oil was 243 degrees and mine was 222. I am actually a little heavier than him by about 20 lbs. Now here's the thing, my engine is all chromed which ought to make it run hotter with that metal jacket encasing it. I have my lowers on and he took his off. Some old timer told me, and I took his word for it, that he found the engine ran cooler with the lowers on. My friend also runs Syn# in all 3 holes. I use Mobil 1 VTwin. I have read many times in this forum that a full synthetic will make our bikes run a bit cooler. I am beginning to think that might be the case here. Do you think: My lowers really are making a difference in cooling the bike, or the Mobil 1 is doing the trick, or is it possibly a combination of the two? Thanks.
  2. TripleJ

    TripleJ Senior Member

    Lots of things can contribute to running hotter or cooler and any difference between the two bikes such as any engine mods. done to each bike, running stock 02 sensors, air filters, exhaust, fuelers, etc.

    I am a firm believer in the fully synthetic oils far as cooling things down. Can't say about the lowers though but am interested to hear what others think.
  3. Bodeen

    Bodeen Well-Known Member Staff Member Moderator Contributor

    I would be more interested in what the thermometers would say if you made note of you temperatures and then swapped dipsticks and re-read. Maybe they aren't that different in temperature?
    Knowing the dipsticks are probably different but I think you could still measure temp.

  4. rkrdr2

    rkrdr2 Active Member

    It's hard to compare a 03 88in to a '08 96in...The 96in motors are so much more EPA controlled than your '03 was its not funny...I'm sure the Mobil1 is helping you out,but even with dino oil in an '03 it will run cooler than a 96 that hasn't been modified to offset the all EPA restrictions.
  5. flhrrider

    flhrrider Member

    Lowers. With them on I can feel no air on the aft side of the air cleaner at highway speeds. Remove 'em and there's a nice breeze there. I can't believe that it's running cooler with less airflow. This is on my '09 FLHT. Just saying.
  6. Breeze3at

    Breeze3at Well-Known Member

    Like the previous posts mention, many variables come into play. I think 10% different readings is pretty close. Esp. between an '03 and an '08. If you ever get to ride with him again, swap gauges for a while and see if that narrows the range.
  7. gator508

    gator508 Senior Member


    I would think the main difference is the engine size, you are running an 88 and your buddy a 96, I can attest the 96 is a hot running beast. The difference of ~ 20 degrees is not much, like Breeze3at said.
  8. Porter

    Porter Junior Member

    Too many variables. Error in the thermometer, whether they were in calibration or linear, different motors etc. I would believe a 20 degree difference was in the "noise" of the system. If you are using a synthetic, I don't think either temperature is bad. If you are using dino oil, it is still not that bad, and if you change the oil regularly, there should be no issues.

    I have and UC with lowers. I feel cooler with the lowers off, but I have not noticed any difference with them off or on as far as my oil temp gauge can measure. Maybe other have, but my gauge doesn't change. Perhaps it is possible that the lowers could force more air past the engine (if they were on) or let more air by (if they were off) but the limit is on how much heat the air can absorb. That is why radiators don't get any thicker for more cooling, they get taller and wider (more area). From the front edge of the radiator to the back side, that is all the heat you can put into the air. Similar with the air going past the V-twin and some of the reason the rear cylinder runs hotter. At least that is my way of thinking...
  9. Hoople

    Hoople Account Removed

    That's nothing. Run each bike side by side at idle sitting still for 3 minutes. Check his HEAD temperature Vs Yours and I bet your eyeballs will pop out of your head.

    I have a friend who rides an early "88" Heritage and he can almost sit and idle all day while I have only minutes.

    I don't fully understand why, but they are just two different animals.
  10. horizonchaser

    horizonchaser Senior Member Contributor

    Thanks guys. I had thought afterwards that maybe if we had swapped digital dipsticks the readings might have been different. And like I said about the lowers, I had only heard a positive testimonial from this old timer as to how much better they were if they were on and not off but I really hadn't put it to any definitive test. I just figured I would throw it out there to the forum and try to gain a better understanding.