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Hello everyone,

My apologies if this topic has been thrashed.

How critical (in reality)is getting oil temp to 50°C before increasing revs above 2500. Inspite of taping over one of oil coolers, I have to wait 10-15 min to get OT to 50° with air temp between 2-10° C and often get "stuck" at mid 40s without gently increasing revs. 

It seems to me that an equilibrium is reached where heat in (from combustion) is balanced by heat out (cooling air flow) and without more heat (revs) 

I'm told that below 50° the oil is too viscous and will bypass oil filter at higher revs - is this true?

I use Aeroshell Sport Plus 4 which is rated 10W40. On the attached graph (viscosity vs temp) there is relatively little reduction in viscosity between 40° and 50° .

Is Rotax being overly cautious? What are others doing in the real world?

Inflight OT range 70° - 100°C .

Appreciate your thoughts, Mark Robertson

 

 

8203_1_Graph_Oil_MobilS_10W40_1024.png (You do not have access to download this file.)
  • Re: Oil temperature/engine warmup

    by » 6 weeks ago


    I installed this oil temp regulator, fast warmup and perfect temperature control summer and winter.

     

    https://www.aircraftspruce.com/catalog/eppages/xcomthermostat.php

     


    Thank you said by: Mark Robertson

  • Re: Oil temperature/engine warmup

    by » 6 weeks ago


    I beleive the rpm limitatation based on oil temperature is to prevent the possibility of oil OVER pressurization which could blow-out the oil seals which would result in no oil pressure and damage engine.


    Thank you said by: Mark Robertson

  • Re: Oil temperature/engine warmup

    by » 6 weeks ago


    Presumably you can monitor your oil pressure.  I think you are fine in gradually bumping up the rpm if/when you get stuck in the low 40s;  if the pressure shoots up to a "high" indication, that would be an indication that you are increasing rpm too fast.

    However, I do think your in-flight temperatures should always be able to reach about 90º.  70º seems too low.  Perhaps there is something not quite right with your oil coolers?


    Thank you said by: Mark Robertson

  • Re: Oil temperature/engine warmup

    by » 6 weeks ago


    As Garrett and Tyler stated, the limit is really the Oil Pressure, Not the Oil Temp or RPM.
    It is just easier to say, "Don't rev up the engine until the Oil Hits 50°C than it is trying to explain what I am about to suggest.
    Try this next time...

    Let the engine heat up for a few minutes at idle.
    Then advance the throttle until the Oil Pressure reaches 60-65psi.
    Once it heats a lillte more and the Pressure drops to 55psi, Advance the Throttle to re-establish 60psi.
    Repeat as needed.

    You should be at 50°C+ in no time.
    You should also notice that at 50°C+ you can no longer produce 60psi at any rpm. 

    - - -

    <<< Inspite of taping over one (of the) of oil coolers... >>>
    How many Oil Coolers do you have.???

    <<< Inflight OT range 70° - 100°C >>>
    That is a lot of Spread, Can be more specific???


    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Bill.Hertzel@Yahoo.com
    Clicking the "Thank You" is Always Appreciated.


    Thank you said by: Mark Robertson

  • Re: Oil temperature/engine warmup

    by » 6 weeks ago


    Hi Bill,

    Yours and previous comments make sense. Iam able to monitor oil pressure so will pay it more attention.

    My setup has 2 oil coolers and the operating oil temperature range varies with engine load - climbing, cruising etc.

    Regards, Mark  


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