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John Womer

Low oil temperature on cold mornings

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Some engine installations don't require an oil cooler. IF this is possible you eliminate a source of unreliability, and keep things as simple as you can.. An inflight adjustable opening must be an option where you operate over a wide range of temperatures often over a short period. It's not something you have to be "at" constantly like full control cowl gills, but if it lets you warm the oil quicker it must inevitably be capable of making it too hot in other situations. Varying your climb speed should always be tried when temps climb unless absolute climb gradient performance is critical. Nev

 

 

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You should be using a multigrade if the temp is that low........... I use 20w50 exxon elite aviation oil......... Must be available around your way. It comes from the U.S. It means that you are running the engine , at least on start up, on a low viscosity oil. (thin!) and it wont thicken up 'til it gets hot. And it it doesn't get hot it wont increase the viscosity...Win Win....This oil is in the workshop manual as suitable for Jabiru.....................Cheers

 

 

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for general info for pilots with Jabiru engines in the UK I have found fitting one of Stev's TOCA units is covered under minor mod reference 1498 part 2.

 

The advantage of the TOCA is faster warm up of the oil (in my case to 83deg C) and then as the engine gets hot that temperature is maintained even if you then fly to the south of France in the middle of high summer (or any where else for that matter). As a point of interest it would be nice to know if any of our over seas colleagues ever suffer over heating on the Lub oil side.

 

As to oil I thought every one uses a multi grade I use Total Aero DM 15W50

 

 

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these TOCA are specially built for the jabiru with alternative thermostats (I have a 83 deg C) all dependant on the version of the engine you have, I bought mine from Kev Hyam ([email protected] uk tel no: 07415 494717) who will recommend the thermostats you need subject to engine type, but they are actually made by Steve Rance ([email protected]) who makes lots of other wonderful goodies (see attached photo) The TOCA UK BMAA approval is. minor mod approval number 1498 part 2. it is also approved by the LAA

 

164209436_rockercovers.JPG.b62848fe59425eb594a332ad22219fb5.JPG

 

 

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My engine is not cowled and I find it runs low oil temps. I am about to cover the oil cooler and note the effect. I run Phillips 20/50 multigrade aviation oil. Does anyone have experience with electric carb heaters? Don

 

 

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I used to use the Phillips 20W-50 in my 3300 but changed to AeroShell 15W-50. I think she likes the 15 weight oil a little better. Temps always in the mid 80s C

 

 

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Are you sure? Nev

Yes :)

 

Multi grade oil has two figures and the lower one is the ‘winter’ component. The figures relate to the ‘thickness ‘ of the oil. I don’t know what the unit of measure is though. Could be 15 times thicker than water x 10 or summink. And therefore the 50 is 500 times thicker than water. But don’t quote me on that! But the W definitely stands for winter

 

 

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From the UK Drivers Technology website.

 

 

 

VISCOSITY

 

Most oils on the shelves today are "Multigrades", which simply means that the oil falls into 2 viscosity grades (i.e. 10w-40 etc)

 

Multigrades were first developed some 50 years ago to avoid the old routine of using a thinner oil in winter and a thicker oil in summer.

 

In a 10w-40 for example the 10w bit (W = winter, not weight or watt or anything else for that matter) simply means that the oil must have a certain maximum viscosity/flow at low temperature. The lower the "W" number the better the oil's cold temperature/cold start performance.

 

The 40 in a 10w-40 simply means that the oil must fall within certain viscosity limits at 100°C. This is a fixed limit and all oils that end in 40 must achieve these limits. Once again the lower the number, the thinner the oil: a 30 oil is thinner than a 40 oil at 100°C etc. Your handbook will specify whether a 30, 40 or 50 etc is required.

 

 

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Zachary! While looking for what the units represent, I found this popular mechanics article. Might not give those details but helps dispels the idea that ‘oils are oils’. As Sol used to say - “Oils ain’t oils !”

 

How To Pick The Right Motor Oil - Engine Oil For Your Car

 

 

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My engine is installed "un-cowled" so that air circulation around it is unimpeded. I am going to dis-install the oil cooler as the oil struggles to reach operating temp. As oil is forced through the oil cooler before it reaches the engine it could cause starvation when cold. The blocking action of the high resistance oil cooler(it has ID of 6mm entry and exit) could mean that when cold most oil is dumped back to the sump rather than feeding the lubrication galleries. The engine is early fixed lifter and has the deep finned sump, designed originally to run with no oil cooler.

 

 

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You need to get the oil to about 85 degrees C to reduce moisture forming. IF a motor can operate without an oil cooler you are much better off. Quite a few of the GA small flat fours don't require an oil cooler. Large amounts of oil take longer to warm up also. Your POH has a minimum oil temp for flight.It's a MINIMUM. A bit above doesn't hurt either if you have obstacles around the perimeter or hills to climb over. Nev

 

 

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JAbiru state minimum 50 deg before take off, maximum continuous, 80-100 C and max peak 118 C

 

These relate to a probe in particular spot in sump

 

With such a small volume of oil, temps are sensitive to oil level load and cooling capacity.

 

 

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The very early Jabirus had no oil cooler. They were adamant that it was not needed. But it turned out they were wrong, because the sender for oil temps was too close to the sump wall and giving readings too low. My SK kit ( 1998) was one of the first to come with an oil cooler.

 

 

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I admit to being somewhat reluctant to go against Jabiru advice on this. However, the air temps are so low now and the oil takes forever to get to operating temp that I will loop a tube around the OCA and re-consider including the cooler when ambient temps increase in Spring. Thanks for your posts. Don

 

 

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And 10w/40 aviation oil is available....where?

I agree with this, and it is supported in the Jabiru Engine Manual (JEM0002-7 Page 17 (Sect 3.8)), for operating in those temperatures.

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