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Engine oil degrading quickly

Discussion in 'Bling and Appearance' started by port80, Jan 14, 2008.

  1. I try to change my engine oil every 4,000kms - give or take 500kms. There is obvious improvement after every oil change. 9,000kms ago I changed oil (Motul 5100 10w50 as usual) and oil filter (K&N 303) as well as change the air filter (K&N). The bike felt much better and reved smoothly. At this point the chain and sprockets were only a couple thousand kms old and well adjusted. I also did an oil change about 4,500kms ago.

    On the weekend I changed oil and filter (same as per above), I also gave my chain a good clean and wax. I jumped on the bike to run to work this morning and gave the bike a bit of throttle in one of my favorite areas, I quite literally was almost tossed off the back of the bike. Sure I wasn't holding on with deathly tight grip, but I really wasn't expecting the pull it gave. It was revving so much faster and smoother than just a couple of days before.

    I try to but good (95RON - BP/Mobil) fuel in her all the time.

    My questions is, should I be concerned with the amount I difference in the bike when I put new oil in her? Considering the oil is less than 5000kms old.
  2. If you think that's good, wait till you get the new spark plugs in!

    Isn't it great when your bike runs well...
    a lot of that improvement might have come from the scrub and
    re-wax of your chain.

    I wouldn't worry about something being wrong with your bike,
    because you've obviously just fixed it :D
  3. I doubt it would be the oil, rather it would be the air filter giving you the extra grunt.
  4. +1 for the fresh chain lube.
    I know I'll get flamed for my method of lubing my chains but I use a race stand and run the bike in gear.
    The revs noticeably rise when on the stand with the lube job completed compared to how it was 10 seconds prior.
    Obviously its easier to pull the lubed chain than an unlubed chain. I lube every 3-400k while commuting.

    If your old air filter was cactus for some reason that will make a difference but this time of year engine oil would have to be pretty old for new oil to surprise you. Different in winter however.
  5. But the thing is I didn't touch the air filter this time around. Last time I did it (about 10,000kms ago) it made a good difference.
  6. If you are getting improvements of the magnitudes you a raving about you are letting your chains run too long before doing a lube.

    Air density (the weather) can noticably affect a free breathing engines performance; so consider that too.
  7. Well I tend to do a good lube every two tanks or once a week, which ever comes first. The chain never looks dry - if anything it was a bit gunky.

    The weather this morning was great, nice think fresh air, I do notice that make a big difference to the engine on the bike.
  8. It wasn't the oil change.

    If it was no one (that I know of) has managed to show such an improvement via dyno testing.


    Trevor G

    PS. Maybe you just gave it more throttle!
  9. Degraded oil generally goes thin. I'd expect an engine running knackered oil to give a (brief and marginal) power improvement due to lower losses in the oil pump etc.

    Depending on the engine, I'd believe an improvement in noise levels, smoothness and gearchange quality though. That does happen, although how much is psychological I wouldn't care to comment.
  10. Guy Allen wrote an article years back stating he saw just that, a recorded but small power increase at the rear wheel after lubing the chain.
  11. An oil change will not yield super responsive throttle all of a sudden. The high RON or high density fuels will also not make a difference.
    RON of a fuel has nothing to do with increases in performance, it simply ensures no ping/pre-ignition.
  12. That is quite believeable, since I know from first hand experience what a bad, even though sealed, O-ring chain will do.

    Some dyno companies insist on having a new chain fitted before a run, but I don't know how far they allow you to travel on an "old" one, then, before the subsequent runs.

    But engine oil change? After less than 5,000 km? I'm still waiting. ;-)


    Trevor G

    PS Engine oil can go "off". I have now seen two sumps full of "grease" after the owners neglected to change the oil at the right time. The bearings had also collapsed by then.

    One was a Toyota Hi Lux diesel at 20,000m km of the same oil. The other was a Ford Fairlane on petrol at less than 10,000 km (or so the customer insisted).

    Both used mineral oil (known as "dino" in the US). Synthetic oil will go considerably further, that's why they use it as additives or as the full thing.
  13. My bike and car idle more smoothly after an oil change and the bike feels a bit more responsive too. That's my experience.

    The old oil may be less viscous, but I don't think that equates to better lubrication properties. A thinner oil probably results in HIGHER internal friction between moving parts.

    Frankly I'm not surprised that a change of oil and a good chain clean can make a difference that you can feel in the seat of your pants. To my mind, it stands to reason - an easier spinning engine (less internal friction) and less friction in the chain delivering the power should lead to an improvement you can feel.

    A lot of hoopla is made about how lubing oring chains doesn't make much difference, but my practical experience says otherwise. Very regular chain maintenance on my previous 900cc bike saw 42000km before semi retirement of the bike. That was with the original OEM chain and it still had plenty of life left. Those 42K included 15+ track days and all other kinds of riding.

    Folks that fit the Scott oiler often claim chain lives far in excess of my experience... the oil must be doing something other than simply coating the roller.
  14. I certainly wouldn't claim lower friction from old oil. I'm not basing my opinion on anything other than a vague gut feeling that, in the short term, the lower power requirement of the oil pump (due to lower viscosity) would outweigh any increase in frictional losses. I'd also add the disclaimer that I'd expect any net difference to be so small as to be undetectable against the substantial medium to long term power decrease due to your cams having ground themselves to powder :grin: .

    On the subject of worn out oil, the best case I ever saw was an old Morris Oxford that had done 150,000 miles without an oil change (200,000 miles total), although it had leaked/burned plenty. When the engine was eventually replaced, the oil appeared to have separated into a thin, kerosene-like substance which was presumably what was actually circulating and doing the lube duty, and several inches of a thick sludge in the bottom of the sump that looked as if it should contain dead seagulls (and which needed a screwdriver poking through it in order to drain the kero) :grin: .

    Interestingly, the car went like the clappers (by 1966 Morris Oxford standards anyway), presumably because all the bearings and the bores were so loose that there were no frictional losses to speak of. With the kero lubrication and the worn crank, it didn't start to show oil pressure until you got the revs up a bit anyway.
  15. If I were trying to come up with a logic I would be thinking the old oil was giving off vapor that was throwing off the FI due to recirculation.

    but that really is clutching at straws. It's all in your head is a more plausible answer.
  16. No FI, it's a carby model :(

    Some think it may be in my head, but I know my bike very well - I ride it on the same roads every day... Again this morning the bike was a lot more lively than usual - again the weather was fantastic.

    I'm now thinking that the chain being clean may help the bike rev (gain speed) faster and the new oil & filter are making it smoother. Perhaps the new oil filter is reducing the pressure required for the oil to flow?

    Anyway thanks for all the thoughts, this just reinforces that I should keep up the very regular oil changes and make chain cleaning a more regular task (thanks Rob).
  17. Well, next time you need to change your oil I'll pay for a dyno run at an agreed joint that will just charge us for a non-tuning pass.

    We change the oil (and filter if you like) and do another run. As back to back as possible, just allowing for the oil and filter change.

    If you (or the dyno guys) can demonstrate a 2% or more change in performance (horsepower) I'll also pay for the second run. You would never feel that amount of change, but I'm interested if any change at all is visible.

    Should cost no more than $40 to $60 per run.


    Trevor G

    PS My bikes always feel quicker after a service and wash. I don't think they are, tho. ;-)

    Trevor G
  18. Trev, I'm due for an oil change before long... might take you up on that offer!

    Actually, I probably don't need to. I have a pre service and post service dyno run chart (in my garage smeg) from Dynotune in Moorabbin. From memory there's a 2HP difference in peak power. That amounts to 1.5% roughly. I can't vouch for whether that increase was solely due to good service (oil, plugs, lube, clean filter) or due to carby tweaks - but I don't believe Dave got into the carbies and changed float heights etc. ...so it has to be due to the service... and I know the air filter was fairly clean to start with...

    Mind you... I'm not sure one can sense a two horsepower difference...
  19. Trevor, sounds like an interesting proposal. Are you saying you would pay for the first run and me the second? If there was a 2% or greater difference then you would then cover the second run cost?

    Either way, I'm not sure that difference would show up on a dyno (not an expert at these matters) as I think it is faster revving and smoother, not necessarily making more power. Would the faster revving engine gain speed (accelerate the bike) faster?

    If I'm wrong perhaps somebody could better explain it to me.
  20. I'm wondering if it might be a bit of both;  Rob's noted a difference in HP after a service and there's you to consider too - are you altering your inputs in response to different/smoother engine note, etc. ?  Do you really understand how you control the throttle or is it really pretty automatic?  ;)

    I certainly percieved a small difference in the CBF after the oil change. How much of that was me adjusting my riding due to the engine sounding less sickly I don't know.