Forum Discussion

RambleOnNW's avatar
RambleOnNW
Explorer II
Aug 05, 2014

Onan Microquiet 4000 Oil Analysis

Did an oil change on the Onan Microquiet 4000 and sent in an oil sample for analysis. Got the result back and looks good. Iron is a little higher than average, the average duration is 100 hrs. and I ran 42 hrs., but it still has low hours so may be still breaking in.

I had run this oil, Mobil 1 High Mileage 10W-40 for 2 years, 4 months and decided it was time to change. Did not look all that dirty and looked like it could have gone much longer, however the oil had sheared down into the 10W-30 weight range.

TBN looked good, plenty of acid absorbing capability left.

Had some leftover 0W-40 so that is in there now.

Class C
  • wcjeep's avatar
    wcjeep
    Explorer
    Aug 05, 2014
    I always find these interesting. Some diesel guys really get into testing engine oil.

    Thanks for sharing
  • Jaxom's avatar
    Jaxom
    Explorer
    Aug 05, 2014
    It is my understanding that the first test merely establishes a baseline for subsequent analysis. Changing oil and duration would skew the results.
  • RambleOnNW's avatar
    RambleOnNW
    Explorer II
    Aug 05, 2014
    The universal averages for all users with this type of motor is in the right column, based on an average of 100 hrs of use. So some comparison is possible. I'm surprised how much oil shearing there was, that oil should have started out with 14.7 cSt and it sheared down to 10.55.

    I have run the same type of oil in our cars in the 10W-30 weight and over a 4200 mile run it only shears from 12 cSt to 11.15 or so.
  • Handbasket's avatar
    Handbasket
    Explorer
    Aug 05, 2014
    Since the Micro's don't have an oil pump or filter (splash lubed), and are air cooled (higher oil temps?), they may well impose higher stresses on the oil than a car engine.

    Jim, "I couldn't fix your brakes, so I made your horn louder."
  • tpi's avatar
    tpi
    Explorer
    Aug 05, 2014
    It would be interesting to see how much the 0W40 shears. I have that in my Onan. Am I correct in reading that the 10W40 sheared into a heavy 30 weight?
  • RambleOnNW's avatar
    RambleOnNW
    Explorer II
    Aug 05, 2014
    Viscosity at 100 deg C, 30 weight range is 9.3 - 12.49 cSt, 40 is 12.5 - 16.29. The 10w-40 HM started with 14.7, Mobil 1 0W-40 starts with 13.5.

    For comparison, Mobil 1 10W-30 starts with 10.1, 10W-30 EP starts with 10.2, so yeah, ended up a little higher but wouldn't call it a heavy 30 weight. Mobil 1 10W-30 HM starts with 12 cSt.

    Will check back in a couple of years on the 0W-40...
  • tpi's avatar
    tpi
    Explorer
    Aug 06, 2014
    I suspect 15W40 Delo or Rotella would give very good wear numbers in these generators. Possibly nothing could be better. I like the synthetic 0W 40 for cold weather use and trying to get some load off the starter parts. I use it year round and think it should protect fine in hot weather.
  • bobojay5's avatar
    bobojay5
    Explorer
    Aug 06, 2014
    It's interesting that Onan's diesel RV generator specifies only non-synthetic oil be used. Possibly because the diesel motors for that one are made in Italy?? who knows. Their gasoline and propane models don't say that. At least the ones I've had.
    In the diesel gen we had I used Rotella 15w-40 with good results, and in the gas and propane models I use/used, I installed Amsoil 10w-30 4 stroke synthetic with good results. Good results for me is oil stays clean, and doesn't use any.
    My yearly usage is somewhere between 25 and 50 hrs, so no big deal there. And I change it once a year anyway in the late fall.
  • RambleOnNW's avatar
    RambleOnNW
    Explorer II
    Apr 15, 2015
    Here's an update: have run the 0W-40 the rest of last year and through the winter and the 0W-40 starts up much easier than past oils after sitting for a while, up to 6 weeks. Will likely run to 2 years before changing.
  • fireflock's avatar
    fireflock
    Explorer
    Apr 16, 2015
    I've been very tempted to have both our Onan 4000 generator and V-10 engine oil sent off for analysis. Each time I look at the cost and decide to spend the money changing the oil instead.

    Am I being penny wise and pound foolish? Is there something more useful to learn than change the oil now or just keep running it?

    I've resigned myself to changing the oil more frequently than I probably need to because the DIY cost is similar to the cost of analysis.

    I understand it's different for diesel engines where oil change expenses are higher.

About Motorhome Group

38,705 PostsLatest Activity: Jan 20, 2025