Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Mixing Oils  
User currently offlineAtlasAir From United States of America, joined Jun 1999, 119 posts, RR: 0
Posted (14 years 6 months 1 day 4 hours ago) and read 5667 times:

Lets say you have an engine that has sticker that says MOBIL JET II.Question is can you add an oil from another conpany, say Chevron or 2380?


8 replies: All unread, jump to last
User currently offlineBuff From Australia, joined Mar 2007, 0 posts, RR: 1
Reply 1, posted (14 years 6 months 1 day 3 hours ago) and read 5623 times:

My recall (as a pilot) was that with Turbine oils it was best not to mix manufacturer types, but not forbidden. As long as the MIL Spec was identical, in a pinch it was OK to mix.

Recip oil types were restricted to detergent/non-detergent based oils of the same viscosity. Don't mix "W" oils with non-W; only use non-W when breaking in a new engine; multi-viscosity oils generally not approved.

An engineer's perspective would be more legit than my humble recollections, of course!

Best Regards,


User currently offlineJT-8D From United States of America, joined Dec 2000, 423 posts, RR: 3
Reply 2, posted (14 years 6 months 1 day 3 hours ago) and read 5621 times:

As a rule, on jet engines, dont mix. We switched from Exxon 2380 to mobil 254 many years ago. The oils were supposed to be compatable. After numerous filter clog lights, and delayed departures, it was found that the oils where not compatible. Little black balls where found in the oils strainers. When the procedure came out to drain out the old oil, then refill with new, there was so many of these ball things in the oil tank that when we removed the drain plug, the oil wouldnt come out. Had to poke a screwdriver into the hole to get it to drain. As buff said, you would expect oils to be compatible if they are the same mil-spec, but I guess not..JT

User currently offlineGt1 From United States of America, joined Feb 2001, 133 posts, RR: 0
Reply 3, posted (14 years 6 months 15 hours ago) and read 5596 times:

I would suggest that mixing oils in a turbine engine is not a big deal. In fact, sometimes it is the recommended procedure. The currently accepted method of oil type change-over is the top-off method, which means you simply add the new type of oil to the old oil. Eventually, you end up with a oil system completly full of the new type of oil. Complete change-overs are not recommended because they spike the additive package which causes plugged oil filters. The "little black balls" were bits of debris left by the old oil, and dislodged by the detergents in the new oil. 2380 allways left some carbon in the oil system. 254 is a more detergent oil, so when it is added to 2380, it will cause some filter clog lites to come on. The new oils, Exxon 2197, and Mobil 291 promise to be the best turbine oils yet, but they have a strong detergent package in them, which when added to an old oil system, will be bound to plug some filters, but that is only because they are cleaning a dirty oil system, not because they are incompatable with the old oil.

On the other hand, Sundstand warrenties their IDG's based on oil brand/type. So mixing of oils there should not be taken as lightly.

Please check your companys procedures on this issue. It makes for some interesting reading.


User currently offlineT prop From United States of America, joined Apr 2001, 1034 posts, RR: 1
Reply 4, posted (14 years 6 months 14 hours ago) and read 5595 times:

On PW100's, we are cautioned in the Pratt maint. manual not to mix different brands or types since the chemical structure may make them incompatible.

We are also required to service the prop hub with the same type of oil that's in the engine. We use BP (Exxon) 2380 now, if we wanted to switch to Mobil or some other type, Pratt requires us to drain and flush the engine oil system.

T prop.

User currently offlineTimT From United States of America, joined Jun 2001, 168 posts, RR: 0
Reply 5, posted (14 years 6 months 12 hours ago) and read 5586 times:

The company I work for just changed from Exxon 2380 to Mobil 291. We changed the stickers as far as I know. There was a lot of dealing with engineering about compatibility in CSD/IDG, starter, and generators, but the final bulletin allows mixing.

User currently offlineJT-8D From United States of America, joined Dec 2000, 423 posts, RR: 3
Reply 6, posted (14 years 6 months 3 hours ago) and read 5569 times:

GT1 has a good point. We tried the topoff method, and we got the "carbon balls". Thats when we started draining and refilling. Maybe it was just to get rid of the residual? For some reason, half our fleet still uses 2380 in the csds, and all our idgs use 2380 also. Apus seem to be split too. 757 uses 2380, 737 uses 254. Does this make any sence?..JT

User currently offlineAtlasAir From United States of America, joined Jun 1999, 119 posts, RR: 0
Reply 7, posted (14 years 5 months 4 weeks 1 day 23 hours ago) and read 5565 times:

JT-8D what fleet are you talking about?

User currently offlineJT-8D From United States of America, joined Dec 2000, 423 posts, RR: 3
Reply 8, posted (14 years 5 months 4 weeks 1 day 4 hours ago) and read 5542 times:

My companies airplanes is what I mean by fleet..JT

Top Of Page
Forum Index

Reply To This Topic Mixing Oils
No username? Sign up now!

Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)

Similar topics:More similar topics...
Mixing Oils posted Tue Jun 5 2001 18:00:44 by AtlasAir

Sponsor Message:
Printer friendly format