What oil do you use in your Rotax 912ULS?

[facthunter]

Those Nikasil Bores don't give any trouble but rings, valve guides, stems and springs are worth checking. Rust pit on a valve spring will cause breakage later.  Don't think I'd split the cases without reason .  Is it the  earlier 80 HP motor without the Red gear clutch? Nev

[Marty_d]

I remove the plugs, spray Inox in the cylinders and turn the prop to get the Inox around everywhere.  This happens once a month.  I also had a pet bed heater under the motor in really cold winters.  

No it's not the 80hp, 100hp ULS.

2 hours ago, facthunter said:

You may not wish to bother with this at this time.Nev

???  Not quite sure what you mean there Nev.

[facthunter]

At the Moment the engine would not be your first priority?   It will fly OK even if it has square corners. Nev

[fallowdeer]

A 2000hr 912  that had those hours piled on quickly in a flight school while being well maintained is likely to be a better bet than a 12 year old model with 350 hours from what I’ve observed.  

[facthunter]

I think that would vary with individual cases. I'd' be replacing the exhaust valves on a 2000 hour ULs. and probably the rings . Nev

Edited March 3 by facthunter

[fallowdeer]

Each to his own.  My opinions based on direct observations and conversations with probably the two most experienced 912 engineers in NZ, one of whom has been selling and servicing 912s for well over twenty years. 

[BrendAn]

45 minutes ago, facthunter said:

I think that would vary with individual cases. I'd' be replacing the exhaust valves on a 2000 hour ULs. and probably the rings . Nev

i know of a 912 uls that has 3600 hrs in a flying school tecnam. he ran it on condition to 3600 . never had a problem , never pulled apart. still passing leakdowns .

he was allowed to run on conditon because the tecnam has a type certificate. 

 

[facthunter]

If you do what I suggest the Motor will stay cleaner internally and therefore wear less and the EXvalves are the Hardest worked Part. I don't see much point in setting some record for Longest use. It's not a Sydney taxi.  It's an Aeroplane.  Nev

[facthunter]

 Anyhow everything fatigues.  New is best. Nev

[Lyndon]

At two thousand hrs I would suggest the lifters and cam are toast. 

Especially if it's been run out of a school with on avgas. The last engine I built was full of sludge with the cam and lifters being roast. The rest of engine was in good nick. 

Lyndon 

[skippydiesel]

On 29/03/2014 at 7:14 PM, Downunder said:

I've read that semi-synthetic only if running avgas as the lead is not kept in suspension with full synthetic.

 

 

I stand to be corrected:

 

Rotax have gone to a lot of trouble/research to come up with a full synthetic (XPS 5W-50 ) that can be used with AvGas.

Reason being Rotax do not believe that general automotive full synthetics are suitable for leaded fuels.

 

I would go one further - no generally available, modern automotive engine oi, is designed to deal with leaded fuels. If using AvGas use them at your own risk😈

[facthunter]

There's plenty of engines that run exclusively on Avgas and have no issues with Lead even when it contained much more lead than it does today in 100LL.. Being synthetic these days where the Oils will mix  does not mean much but infers better quality and uniformity.. Suitable additives are more often the critical factor, The Rotax requires the oil to serve a multitude of Purposes . The friction part of the Clutch(damper) the Cam of same, the reduction Gear and the General engine with Turbo Boost ( heat and load). PARTICULARLY. That is why it requires a special oil.  There's a LOT of BS about what oils are best. In this case just DO what Rotax SAYS on the ones over 100HP. the 80HP and ULS can use what they always did.  Sludge usually happens when engines don't get to run fully warmed up enough.  Nev

[BurnieM]

My understanding is that the Rotax specified full synthetic oil was developed because the 916 ran hotter than expected and Rotax wanted a full synthetic to handle the heat.

There are known problems with most full synthetic oils not being able to suspend the lead (from Avgas) so a huge amount of testing and changes to the oil additives were performed

until they found a suitable additives package.

 

Appears that the 912UL, 912ULS, 912IS, 914 and 915 can run fine on the Shell aero oils.

 

[skippydiesel]

True! Rotax wanted to use a full synthetic oil to address high temperatures in the 916.

 

Allegedly there were no "off the shelf" oils that would accomodare lead residues, should the engine be run on AvGas

 

XPS 5W-50 was developed to address both the high temperature AND AvGas (lead containing) that may be used.

 

Presumably a good quality full synthetic 5W-50 motorcycle oil, suitable for combination crankcase/gearbox application, would do the job, as long as no significant AvGas usage envisaged.

 

XPS 5W-50 can be used in all Rotax 4/engines 😈