Oil question...I know, dangerous territory

[rangermb]

1977 J here. Just out of latest annual. I've been running Exxon Elite for years, but now it's off the market. We switches to Phillips 20/50 (same grade as the Exxon Elite). 

I have a few quarts of the Exxon on the shelf. What's the general opinion about using it for topping off the Phillips that is now in the crankcase?

Thanks for the wisdom 

[N201MKTurbo]

If you change it often enough, it doesn’t really matter which oil you use.

It makes some feel better to use expensive oil. 
 

If some of these oils were bad, the engine manufacturers and rebuilders would forbid their use. I’ve never heard of this.

[carusoam]

LOP or ROP?

T/O flaps or none?

Fine wires or the other kind?

Searching for small words like Oil needs something as powerful as Google to work…

MS search has difficulty with three letter words, where Google doesn’t.

Best regards,

-a-

[toto]

35 minutes ago, rangermb said:

1977 J here. Just out of latest annual. I've been running Exxon Elite for years, but now it's off the market. We switches to Phillips 20/50 (same grade as the Exxon Elite). 

I have a few quarts of the Exxon on the shelf. What's the general opinion about using it for topping off the Phillips that is now in the crankcase?

Thanks for the wisdom 

Should be totally fine. Go crazy

But seriously, as long as it’s an aviation oil and meets the SAE spec, it should be compatible with every other oil.

https://www.aviationpros.com/home/article/10387125/mixing-piston-aviation-oils-will-topping-off-with-a-different-brand-weight-or-type-harm-the-engine

[PT20J]

A couple of years ago, Continental issued a Service Information Letter, SIL 19-04 Oil Brand Selection, that included the following statement that had a lot of people scratching their heads:

"Switching oil brands before engine overhaul may result in higher wear rates for lifters and cylinder components, even under normal operating conditions."

Mooney reprinted the information in Special Letter 19-09.

sl_19-09-compressed.pdf

Interestingly, I can no longer find the original in Continental's list http://continental.aero/support/service-bulletins.aspx#. Perhaps Continental realized it was silly and revoked it.

Skip

[A64Pilot]

Sometimes or often if you want to say it that way any manufacturer will include a higher level or better additives in there premium products.

I’ve seen Shell make that statement about their 15W-50 compared to their straight weight oils, that the corrosion resistance is higher.

I was a friend of the local Chevron jobber, the guy at the ends of the pipeline who blends the fuel etc and he said that the amount of Techron was higher in Premium fuel than regular for instance, so not all premium products are just hype. 

I used my last case of Exxon Elite myself not long ago. shame they just quit, apparently they weren’t making enough money?

So once Elite went away I went to Shell 15W-50, It’s interesting the number of people who think that single grade 50W will stick to the cam better on shut down because it’s thicker.

It’s not thicker when hot, only when cold, when hot the viscosity is the same 

[StevenL757]

On 10/10/2021 at 9:15 PM, rangermb said:

1977 J here. Just out of latest annual. I've been running Exxon Elite for years, but now it's off the market. We switches to Phillips 20/50 (same grade as the Exxon Elite). 

I have a few quarts of the Exxon on the shelf. What's the general opinion about using it for topping off the Phillips that is now in the crankcase?

I ran Exxon Elite for the life of 2 engines thus far.  Never an issue with either engine.

Personally I wouldn’t mix and match.  Run the Philips XC Victory (with the corrosion and anti-wear additives over and above the Philips XC), and donate the Exxon to the nearest oil recycling facility…unless you know someone who still has a stockpile of the stuff who can take it off your hands.  Best oil I’ve ever used.

[toto]

19 hours ago, StevenL757 said:

donate the Exxon to the nearest oil recycling facility…unless you know someone who still has a stockpile of the stuff who can take it off your hands.  Best oil I’ve ever used.

My experiences with synthetic aviation oil are something like:
* Mobil AV-1 was the best by far
* Exxon Elite was second-best, only used after AV-1 was pulled
* Aeroshell 15w50 was never quite as good as Elite, stopped using in favor of XC+CamGuard

If anyone wants to go back to AV-1 and needs to buy a case or two or ten, I might know a guy

 

[PT20J]

2 hours ago, toto said:

My experiences with synthetic aviation oil are something like:
* Mobil AV-1 was the best by far
* Exxon Elite was second-best, only used after AV-1 was pulled
* Aeroshell 15w50 was never quite as good as Elite, stopped using in favor of XC+CamGuard

If anyone wants to go back to AV-1 and needs to buy a case or two or ten, I might know a guy

 

Define “best”

[toto]

21 minutes ago, PT20J said:

Define “best”

Clearly a very subjective assessment

Used AV-1 in an O-360 for 2500 hours with essentially no change in oil consumption and no change in compression over the life of the engine (well, the life of the overhaul, anyway). Did a major at 2500 just because it seemed like borrowed time, but there were zero problems with the engine. Started using Exxon Elite after the major, and compressions were worse with worse oil consumption (and ended up getting hit with a fun 50-hour recurring AD on ECi cylinders too). 

I know that the AD, oil consumption, and compression likely has nothing at all to do with the post-break-in oil (likely more to do with the break-in itself). But subjectively I liked the AV-1 better because it did everything I could ask of an oil, and nothing else 

 

[LANCECASPER]

Mobil AV-1 was only out from 1987-1995, just under 8 years. It was actually pulled in 1994 but Distributors kept selling it part way into 1995.

If people did frequent oil changes it was probably ok, if not, lead sludge built up.

https://www.avweb.com/features/mobil-av-1-under-attack/

https://resources.savvyaviation.com/wp-content/uploads/savvy_pdf/Savvy-Oil-Recommendations.pdf

 

[toto]

17 minutes ago, LANCECASPER said:

Mobil AV-1 was only out from 1987-1995, just under 8 years. It was actually pulled in 1994 but Distributors kept selling it part way into 1995.

If people did frequent oil changes it was probably ok, if not, lead sludge built up.

https://www.avweb.com/features/mobil-av-1-under-attack/

https://resources.savvyaviation.com/wp-content/uploads/savvy_pdf/Savvy-Oil-Recommendations.pdf

 

Every 50 hours in my case, vs the Mobil allowance of 100 hours (which obviously was a bit optimistic). 

My understanding of the sludge situation was that it mostly affected big-bore Continentals. The most notable thing I remember about it was that Dick Collins had a very public fight over engine damage from the oil, which was probably the worst PR the product could have had.

[Shadrach]

People are religious about oil brand. Any oil approved for a given application can be mixed with another oil approved that application. Obviously one should consider start up oil temps when adding straight weight oils.

[philiplane]

On 10/11/2021 at 5:50 PM, A64Pilot said:

 

It’s not thicker when hot, only when cold, when hot the viscosity is the same 

Well, not 100 percent accurate. Multi-weight oils are made from the lower viscosity base stock (15, in the case of 15-w50), and they use modifiers that make it act like the 50 weight when it gets hot. The trouble is, the performance over time, and at various temperatures, is not uniform. After some time in service, and depending on the temperature, the 15w50 may be acting as 30, 40, or 50 weight under conditions that the straight 50 weight is, well, 50 weight. 

As for clinging to parts after shutdown...as a multi weight cools, it thins, so yes, it will tend to continue dripping as it cools. A straight weight will not. 

I can see this in oil temperature and pressure plots when pilots using multi weight oils report low oil pressure. Especially in Continentals, that don't have high pressure to begin with.  The fix is a fresh change of oil. 

Edited October 13, 2021 by philiplane

[buddy]

My oil distributor, Fornell Oil told me not to mix oil when I went from Aeroshell 100 Plus to Phillips 100 AW.

[A64Pilot]

3 hours ago, philiplane said:

Well, not 100 percent accurate. Multi-weight oils are made from the lower viscosity base stock (15, in the case of 15-w50), and they use modifiers that make it act like the 50 weight when it gets hot. The trouble is, the performance over time, and at various temperatures, is not uniform. After some time in service, and depending on the temperature, the 15w50 may be acting as 30, 40, or 50 weight under conditions that the straight 50 weight is, well, 50 weight. 

As for clinging to parts after shutdown...as a multi weight cools, it thins, so yes, it will tend to continue dripping as it cools. A straight weight will not. 

I can see this in oil temperature and pressure plots when pilots using multi weight oils report low oil pressure. Especially in Continentals, that don't have high pressure to begin with.  The fix is a fresh change of oil. 

Your correct in there Multi Vis oil is the lower weight oil with viscosity improver additives to keep it from thinning out at higher temps, temps well above what we run at.

Also the VI additive package is among the first additive package to break down in oil, but it should last well beyond 50 hours before it begins to break down, and I rarely make 50 hours as I usually only fly 100 a yr and change oil three times a year, and I think I’m common. Some I suspect change at 50 regardless of how long it takes to get the 50 though.

Any oil that’s going to drip off of a cam will do so soon after shutdown while it’s hot, multi vis oil doesn’t thin when it cools, it’s viscosity should remain the same, however straight weight oil will thicken as it cools, so at say room temp straight weight 50 is much thicker than 15W-50. 

Beside the cost. I can’t make a case for not running multi vis oil and I don’t live where it’s cold.

[M20F]

 

[A64Pilot]

I bet a completely opposite view, but it’s mostly from the actual oil manufacturers themselves so not as legitimate a source I guess

https://www.aviationconsumer.com/maintenance/the-oil-argument/

[Peter Rejto]

Wow, AV-1 the "best." Yikes, I'd have to disagree with a vengeance. 

I ran AV-1 in my Firewall Forward HorsePower Plus engine  for several years....had all sorts of issues with blowby (most likely due to an inability to ever properly break in this engine in spite of at least 3 complete cylinder replacements under warranty!)  - but had the same blowby issue using Shell straight weight oil.  Then I received a frightening call from my mechanic who simply said "You'd better come down here to have a look at your engine." (The prop was pulled for an OH). The crankshaft oil passage into the prop hub was 90% blocked with sludge, and it wasn't for lack of 25 hour oil changes. I was one of many receiving compensation for engine OH. I gave up on the HP+ and have been extremely happy running XC 20-50 + Camguard. 

Peter 

[toto]

2 hours ago, Peter Rejto said:

Wow, AV-1 the "best." Yikes, I'd have to disagree with a vengeance. 

I certainly wasn’t trying to say that AV-1 is the best oil. It has well-documented problems. I was saying that among synthetic aviation oils, I had the best experience with AV-1 of the lot. I’m currently running XC with CamGuard in the Mooney.

[A64Pilot]

Unfortunately Mobil chose to use a PAO base oil, and PAO is excellent oil with many great virtues, but it doesn’t dissolve lead like group 3 and less oils do.

Mobil -1 could have “fixed” the problem with an additive, but chose to just bail as the exposure wasn’t worth the small profit to be had. 

However the meaning of “Synthetic” doesn’t mean much anymore, not since Castrol started selling group 3 oils years ago and calling it synthetic, which most will agree that’s it’s not. So many manufactures advertise synthetic or synthetic blend, for oils that really aren’t.

So the Lawyers have redefined the meaning of synthetic, sort of I guess like it depends on what your definition of the word, is, is.

I cut pasted the below from Wikipedia, I’ll give you the link too.

In 1998, Mobil sued Castrol over the discovery that Castrol was processing conventional oil and calling it synthetic. At the time, Mobil 1 was still created using a true synthetic basestock, which is more expensive. Mobil lost the lawsuit, and, as a result, the "new" definition of 'synthetic oil' became much looser. In order to stay competitive, Mobil needed to downgrade their process to the more affordable process. The result is a hydrocracked, hydroisomerized conventional oil. Lubes N' Greases magazine has reported shortcomings in the ability to pass the tests that the original Mobil 1 formula was able to.^[3]

https://en.wikipedia.org/wiki/Mobil_1

Strange thing was many especially Lycoming customers had great results with the Mobil oil. and some had really bad issues with it, it’s likely that the engines with higher blow by and oil consumption were the ones with the worst problems.

Many engines with higher oil consumption and blow by make good power and last a very long time and other than feeding them a little more oil they are just as airworthy as ones that burn little oil. so I am not inferring that only old wore out engines were the ones with problems

Edited October 15, 2021 by A64Pilot

[Mooneymite]

I'm getting ready to change the oil in my "other plane", not my Mooney, but a Lyc O-320.  I've been using Aeroshell W100.  Living in the south, cold weather ops are not an issue, but I just happened to look at this Lycoming SI on oil.  I was surprised at the temp ranges for SAE 40 and 50.

https://www.lycoming.com/sites/default/files/SI1014N Lubricating Oil Recommendations.pdf

Looks like I could be running 80 W about 9 months of the year based on "ambient temperature at startup".  

[toto]

59 minutes ago, Mooneymite said:

I'm getting ready to change the oil in my "other plane", not my Mooney, but a Lyc O-320.  I've been using Aeroshell W100.  Living in the south, cold weather ops are not an issue, but I just happened to look at this Lycoming SI on oil.  I was surprised at the temp ranges for SAE 40 and 50.

https://www.lycoming.com/sites/default/files/SI1014N Lubricating Oil Recommendations.pdf

Looks like I could be running 80 W about 9 months of the year based on "ambient temperature at startup".  

Interestingly, Aeroshell lists 21C as the top temp for W80. (This is more a marketing page than a spec page, idk.)

https://www.shell.com/business-customers/aviation/aeroshell/piston-engine-oil/w80-w100-w120.html

”AeroShell W80 for cold climate regions (-17 to 21°C)”

[A64Pilot]

Look at the top of that chart, and explain why not run the multi-vis oil?

From an engine perspective it wants the lowest viscosity oil that will maintain good pressure, the reason is the lower viscosity oil will have a higher volume of flow and oil does more than lubricate, it’s a coolant for pretty much anything that moves in an engine, the higher flow rate will cool bearings and the cam etc better. The highest loading / most stress is the cam / lifter interface. it’s steel to steel there bearing material wouldn’t survive.

The advantages of multi viscosity oil go far beyond just having oil pressure sooner on start up 

On edit OAT is at best an inaccurate way to determine proper oil viscosity if your going to stick with a straight weight oil as of course an engines oil cooling capacity will vary greatly between airframes, but it’s about the only way you s make generic recommendations

Edited October 17, 2021 by A64Pilot