Straight Weight Mineral Oil in Lycoming?

[M Towsley]

I am posting this question for Chris Kappler who recently bought the Baker's Lycoming-powered pre-war. He is still having difficulties getting onto the forum. See the question below.

Hackenburg said I should run straight weight mineral oil in that engine. Something about the Lycoming having seven sludge tubes and I didn't need the detergents in the modern oils and mineral oil was better. It was hard to follow what he was saying but, in the end, it almost seemed like he was saying I didn't "need" the modern, fancy detergents but other than that, it didn't matter what I ran as long as it was straight-weight. I don't want to run anything wrong in there but I'm afraid mineral oil has abrasives in it that might not be good long-term. I'd like some opinions if possible. Thank you.

[Mark Bowden]

Re: Straight Weight Mineral Oil in Lycoming?

First question to ask is how far from SMOH or cylinder replacement? Why? The manufacturer or overhaul shop may have requirements so you do not void their warranty.

The quoted individual is in error. Aviation oils do NOT contain detergents. Detergents have metallics in them, do not use them.

Sludge is NOT acceptable in an engine.

Aviation oils are from mineral oil base stock. Mineral oils do NOT have “abrasives” in it. Straight weight oils do not contain AD’s (ashless dispersants), they are not multi viscosity oils.

AD, mutli-viscosity, oils come from the same base stock as straight weight oils. The AD additive package is there to collect and suspend dirt and combustion products to prevent those contaminants from collecting in the engine causing sludge build ups. The additive package transports them to the paper filter for removal or removal when you change your oil.

That’s why it is so dirty. If you wait too long between changes the additive package is all used up and then it behaves like the straight weight mineral oil. It cannot suspend the additional combustion contaminants that keep coming from continued use. The multi viscosity still works.

Think of the additive package like Velcro for carbon and dirt. It grabs ahold of it and hangs on. However their only so much available and then it is “full” and can’t grab any more.

Full synthetic oils come from different base stock and they are not recommend in air-cooled aircraft engines. Automotive use only.

AD oils are not “more slippery” straight weight oil, break-in can be accomplished on either oil type. However, follow the OEM manual or the overhaul shops requirements to preserve your warranty.

How you run you engine is most important for proper break-in than oil type. The requirement for straight mineral oil is an old one that has been codified in the OEM manuals regardless of changes in technology or evidence to the contrary. Lycoming documents require both straight and multi-viscosity, AD oils depending on engine model for break-in hours.

If all you have is a screen in the oil system and not a paper filter, AD, mulit-viscosity is going to be hard to beat. In addition to retaining viscosity and film strength at high temperatures.

Biggest impact on oil and engine health, run it properly then change it often, sooner more so than after 25 hrs.

[Mark Bowden]

Re: Straight Weight Mineral Oil in Lycoming?

I put the following in the ref section. Always go to Continental's site for the current version to maintain compliance. It defines engine lubricants.

SIL99-2C is Continentals Service Information Letter on

SUBJECT: SEALANTS, LUBRICANTS, AND ADHESIVES AUTHORIZED BY CMI

PURPOSE: Provide current application of sealants, threading, lubricants, and adhesives.

COMPLIANCE: During engine installation, maintenance, overhaul or component repair or replacement.

MODELS AFFECTED: All CMI engine models operating with AVGAS (gasoline based) fuel.

I'm sure there is a Lycoming equivalent but I don't have it. Maybe someone else has access to it or Lycoming's support site.

It is nice because it identifies all approved materials for lubes, gaskets, sealants, etc...


Hope it helps, Mark

[3Dreaming]

Re: Straight Weight Mineral Oil in Lycoming?

The engine is a 0-145 Lycoming. It has about 200 hours since major overhaul in the early 1990's. The Cylinders are cast iron and part of the crankcase. The recommendation for the straight weight mineral oil came from the engine type certificate holder.

[M Towsley]

Re: Straight Weight Mineral Oil in Lycoming?

Tom,

So you recommend the straight weight mineral oil for Chris?

[3Dreaming]

Re: Straight Weight Mineral Oil in Lycoming?

Tom,

So you recommend the straight weight mineral oil for Chris?

Marty,

It has been 20+ years, I don't remember what I ran in it. I would have to look at the records to make the decision on what oil to use.

[Guest]

Re: Straight Weight Mineral Oil in Lycoming?

There were some studies done on diesel boat engines back in the 1930's.

They compared cylinder wear with straight mineral oil and with detergent/additive oils.

The wear rate with straight mineral oil was twice that with detergent oils.

The oil industry didn't develop all those additive packages without a reason. Not sure why we have people that think they have no merit.

If the engine has run a long time with straight oil then switching to detergent may stir up all that settled in sludge and crud and make a problem.

[astjp2]

Re: Straight Weight Mineral Oil in Lycoming?

the type certificate holder is using data from 1930 what? modern oils were developed 1990's when? I would stick with the Philips, reduces consumption and you end up with cleaner oil between changes. Tim

[Ragwing nut]

Re: Straight Weight Mineral Oil in Lycoming?

the type certificate holder is using data from 1930 what? modern oils were developed 1990's when? I would stick with the Philips, reduces consumption and you end up with cleaner oil between changes. Tim

Some multi-vis oils do not give enough protection against wear and tend to weep through cases with porosity issues. I know of several radial engine rebuilders that will void your warranty if you run multi-vis oil. The deal with mineral oil especially on an engine that runs cool, it will help prevent glazing of the cylinders. It also breaks down quicker so it must be changed more frequently.

[astjp2]

Re: Straight Weight Mineral Oil in Lycoming?

well i was delivering phillips 25W60XC to Era Classic Aviation for their DC3's back in the mid 90's and the mechanixs told me that their oil consuption went down by 50% between oil changes compared to Shell W100, and that was a barrel every 25 to 50 hours per engine depending on the engine's oil change requirements . DC6'S was the same, 50% was also common for them. Most warranties dont mean squat in aviation anymore....

[PA1195]

Re: Straight Weight Mineral Oil in Lycoming?

There was a time when ordinary non-commercial folks flew enough (because they could and fuel was cheaper) that overhaul shops did enough to compare oils used. Aviation Consumer and other mags would report the findings. Now I'm not sure what their consensus is regarding single vs multi vis oils and engine longevity. Probably varies by engine and type of use but it would still be interesting to compare.

Gary

[Ragwing nut]

Re: Straight Weight Mineral Oil in Lycoming?

well i was delivering phillips 25W60XC to Era Classic Aviation for their DC3's back in the mid 90's and the mechanixs told me that their oil consuption went down by 50% between oil changes compared to Shell W100, and that was a barrel every 25 to 50 hours per engine depending on the engine's oil change requirements . DC6'S was the same, 50% was also common for them. Most warranties dont mean squat in aviation anymore....

yes it does reduce consumption, but it was coming at a price in higher maintenance with cylinder issues and leaks. Its not as big of an issue with flat motors.

[Guest]

Re: Straight Weight Mineral Oil in Lycoming?

There was a time when ordinary non-commercial folks flew enough (because they could and fuel was cheaper) that overhaul shops did enough to compare oils used. Aviation Consumer and other mags would report the findings. Now I'm not sure what their consensus is regarding single vs multi vis oils and engine longevity. Probably varies by engine and type of use but it would still be interesting to compare.

Gary

Other than the charts I saw in the Lubrication Engineers handbook I really never see any data regarding engines and oil.

I have some other lubrication engineering books will look there later.

Mostly comments, opinions, anecdotal evidence show up at websites and forums no repeatable or verifiable data show up.

I had discussions with an engineer from one of the aviation engine manufacturers we didn't see eye to eye. Even in that discussion there was little evidence presented from his side.

Having worked as an engineer for 35 years with engineers and having some subordinate to me from time to time as well I have no problem holding an opinion that apposes some engineer's assertions. They make mistakes and hold on to outdated schemes when revising a scheme could introduce work or personal career risk.

So I find the oil debate to be inconclusive and unconvincing but I suspect that it is also one that is inconsequential since oils are all quite good so whatever you pick your long term costs are about the same. My engine maintenance issues have been related to wear that I could attribute to oil but other things like rust, poor assemble practice, skipping things at overhaul.

That's my opinion.

Dave R.

[PA1195]

Re: Straight Weight Mineral Oil in Lycoming?

Then there's used oil analysis. Apparently it can help detect changes in the oil and components including wear metals. Some folks are religious about its application.

Here's an anecdote. In the early '80's on one Lyc O-320 A2B with about 700 hrs TT while using early formulated Shell 15W-50 for a year I began to see a slight silver sheen in my drain oil after a normal 25 hr change. The pressure screen was clean and no finer filter was available at first to examine. My mechanic sent off two oil samples about 25 hrs apart. Nothing remarkable was noted. This was after about 500 hrs on straight 40W Shell followed by about 200 on the multi-vis.

Then we filtered the drain oil through a fine paper filter and noted some "magnetics". Soon particles large enough to be captured by the pressure screen appeared. Pulling a couple of cylinders let us see cam and lifter spalling especially on the lobes shared by two cylinders. We pulled all 4 cylinders and noted exhaust valve to guide clearances that were tighter than spec due to carbon. Fuel used was primarily 80/87 with occasional but limited auto fuel. The initial silver sheen in the drain oil (best seen with a flashlight) was the first indication of wear. Looks just like that silver dope sprayed on fabric diluted with solvent.

We suspected tight exhaust valves, and possibly some cam/lifter corrosion, contributed to the wear. It may have been due to improper metallurgy in the cam or lifter bodies as well. Drainage off metal parts while sitting at ambient air temps was also suggested.

Cost me $$$$ and I've not used multi-vis oil since for some reason, although Shell soon thereafter added some elixirs to help with corrosion and wear.

There were a few of us locally that experienced a similar problem at that time with that particular oil in similar engines (O-320/360's). We later asked Shell's field rep Ben Visser about this phenomena at a local meeting but nothing was forthcoming.

Edit: The reason I had switched to multi-vis was cold weather ops. I pre-heated the engine prior to flight but it was suggested that multi-vis flowed better to far away parts. Now I ignore that benefit and pre-heat as required.

Gary

[astjp2]

Re: Straight Weight Mineral Oil in Lycoming?

Ben used to give a speal during the IA seminars, that is where I learned about expiration dates on oil. How many people know that oil is only good for 4 years in the container? not many and some will argue but it is a violation to use expired products in an aircraft....by both pilots and mechanics..

Then there's used oil analysis. Apparently it can help detect changes in the oil and components including wear metals. Some folks are religious about its application.

Here's an anecdote. In the early '80's on one Lyc O-320 A2B with about 700 hrs TT while using early formulated Shell 15W-50 for a year I began to see a slight silver sheen in my drain oil after a normal 25 hr change. The pressure screen was clean and no finer filter was available at first to examine. My mechanic sent off two oil samples about 25 hrs apart. Nothing remarkable was noted. This was after about 500 hrs on straight 40W Shell followed by about 200 on the multi-vis.

Then we filtered the drain oil through a fine paper filter and noted some "magnetics". Soon particles large enough to be captured by the pressure screen appeared. Pulling a couple of cylinders let us see cam and lifter spalling especially on the lobes shared by two cylinders. We pulled all 4 cylinders and noted exhaust valve to guide clearances that were tighter than spec due to carbon. Fuel used was primarily 80/87 with occasional but limited auto fuel. The initial silver sheen in the drain oil (best seen with a flashlight) was the first indication of wear. Looks just like that silver dope sprayed on fabric diluted with solvent.

We suspected tight exhaust valves, and possibly some cam/lifter corrosion, contributed to the wear. It may have been due to improper metallurgy in the cam or lifter bodies as well. Drainage off metal parts while sitting at ambient air temps was also suggested.

Cost me $$$$ and I've not used multi-vis oil since for some reason, although Shell soon thereafter added some elixirs to help with corrosion and wear.

There were a few of us locally that experienced a similar problem at that time with that particular oil in similar engines (O-320/360's). We later asked Shell's field rep Ben Visser about this phenomena at a local meeting but nothing was forthcoming.

Edit: The reason I had switched to multi-vis was cold weather ops. I pre-heated the engine prior to flight but it was suggested that multi-vis flowed better to far away parts. Now I ignore that benefit and pre-heat as required.

Gary