Rotax 912 oil pressure

[Guest bateo]

G'day Guys,

 

I have just changed the oil on my 912 using shell's synthetic 15W-50. In the manual it states that my pressure must be in between 3-5 bar. Previously when plane was purchased it sat nicely at 4 bar until take-off (5000 rpm) and decreased to 3 at cruise (4600 rpm), after doing this oil change, I am finding that it is dropping a tad below 3 (at Cruise).. I am positive I put the right amount of oil in (around 2.9L) at a max of 3L.

 

Should I be worried about the oil pressure dropping below of what the range it should be running at.

 

It shows 4-5 bar at idle,run-ups etc.

 

What could cause this occurance? Should I get it checked before flying again? I have only done .2 flying in it since change...

 

Help would be appreciated, as I only have a limited knowledge about oil pressure.

 

 

[Guest pelorus32]

Hi Sam,

 

I know that both the 912ULS powered Tecnams at Shepparton come with a sticker on the firewall and a note in the POH saying that you should only use "Castrol GPS" (I think I have the oil right but ring Air Shepparton and check).

 

You should talk to the Tecnam distributors or to Bert Flood. Too expensive to get wrong.

 

Mike

 

 

[Guest bateo]

G'day Mike,

 

Spoke to Bruce Stark, He also suggested ''Castrol GPS'' although the oil I am using was fine, (as long as it was the Synthetic oil and had an additive for gearing ratio)

 

Although it has dropped oil pressure down around 2 bar on cruise, it has increased its Rpm to 5100 from 4900-5000.

 

I would like to hear from any other Tecnam owners of their reading of the Oil pressure Gauge while they are on cruise.. Is it below 3? Bruce stated it was normal to be above 1.5 but I wasnt sure due to the aircraft was running between 3-4 bar with the old oil which is a fairly significant difference.

 

 

[Guest Crezzi]

Rotax no longer recommend Castrol GPS for the 912 - apparently after the formulation was changed in some countries (though possibly not in Aus).

 

The current recommendations are in Service Instruction SI-912-016 available on http://www.rotax-owner.com

 

Cheers

 

John

 

 

[WestCoast]

As far as I know, Bert Flood Imports still recommend using Castrol GPS in the Rotax. I would ceratinly be staying away from a "full synthetic" oil if you ever use any Avgas.

 

Regards

 

Dave

 

 

[Wilfred]

why do you say not to use it with avgas

 

 

[WestCoast]

The full synthetic oils have difficulty suspending the lead that works its way into the oil when burning 100LL or 100/130. This can result in the buildup of a lead paste in the oil passageways of the engine.

 

 

[Guest bateo]

The Operators Manual states that if Avgas is used, oil should be changed more often as this occurs. The Motorbike oils used such as Castrol GPS and Shell's fortified synthetic SX4 is used to lubricate and maintain the high gearing ratio's of the 912's. These oils are not fully synthetic, and also arent mineral based either.

 

 

[Paul Willett]

I am getting around 2.5 bar using Castrol GPS. (912ULS)

 

 

[Guest bateo]

Thanks Paul,

 

Mine was much higher before hand but now running at around 2.5 aswell.

 

I wasnt sure if it was too low or not, obviously not.

 

 

[Guest pelorus32]

I've had a chat to a couple of people about this. It is quite a fraught area and you are strongly advised to go to Bert Flood for an answer. The info so far:

 

1. Shell apparently will tell you that their oils result in a loss of oil pressure and that the pressure falls further over time;
    
    
   
2. Bert Flood apparently still recommends Castrol GPS;
    
    
   
3. It appears that none of the oils is entirely satisfactory in scavenging the lead from the Rotax engines - some are better than others;
    
    
   
4. Shell and others are reported to be working on an oil that will work effectively with the Rotax.
    
   

 

Bottom line: a new 912ULS is quoting at around $22K at the moment. Spend your $0.50 and ring Bert Flood and get the low down from them. Too expensive to stuff around.

 

Regards

 

Mike

 

 

[Guest bateo]

Thanks Mike,

 

Will enquire tomorrow,although I have done 3 hours since the oil change and seems to be running much better, holding increased Rpm, smooth idle, lower oil temp and pressure.. All's the logbook from the previous owner stated was the oil was a 15-40w with 2% additive for gearing ratio.

 

 

[WestCoast]

For those who may have not seen it, this is quite a good article on oil for the Rotax 912.

 

http://www.sportpilot.org/magazine/feature/2004%20-%2010%20October%20-%20Power%20On.pdf

 

 

[Guest bateo]

Thanks westcoast,

 

Well the final word I recieved was that GPS Castrol is the most recommended for the 912 ULS, although the Shell SX4 is similar with a higher additive content for lubrication of the high gearing ratio.

 

I will change oil next 50 hourly to GPS, will be interesting to note the differences in RPM, oil pressure and temp from the 2 oils.

 

 

[hihosland]

For those who may have not seen it, this is quite a good article on oil for the Rotax 912.http://www.sportpilot.org/magazine/feature/2004%20-%2010%20October%20-%20Power%20On.pdf

Be aware however that what is marketed as brand XXX formulation YYY in one market ie USA is not necessarily the same as a similarly labeled bottle in another market ie Australia.

 

Davidh

 

 

[barandbrew]

Hi

 

We have been running Shell SX4 since the engine was replaced 1000 hrs ago in our Gazelle and have not had any problems . The first 500 hrs was on Av Gas oil change every 50 hrs the last 500 hrs on Premuim Unleaded with 50 hr oil changes. Should we expect problems?

 

John

 

 

[Guest bateo]

G'day John,

 

I don't think you should be worrying. The final word I recieved was that Shell SX4 is quite similar to the GPS... In fact Shell SX4 is the best motorbike oil available in Aus for high gearing ratio..

 

I have done 15 hours since oil change and have noticed massive improvement with SX4 (GPS not being available locally)

 

I am considering to change to GPS next 100 hourly to record the differences, otherwise SX4 so far, is running beautifully.

 

 

[Guest Dick Gower]

How is your oil temperature related to this Sam?

 

It is critical on the Rotax 912 to have it well into the yellow because, unlike every other engine I have flown, the oil cooler on the 912is on the suction (inlet) side of the oil pump not the delivery (outlet) side. If the oil is cold, the oil pump can not pull a sufficient quantity through the cooler for adequate lubrication and the pump appears to cavitate (ndicated by fluctuating oil pressure).

 

I think this is why there is a red line at the cooler end of the oil temperature gauge.

 

On a conventional cooler arrangement the pump builds up sufficient pressure on the inlet side of the cooler to ensure adequate flow and therefore oil temperature is not such an issue.