Silver 6V-92 with 15W-40?

[5B Steve]

Thought I would share this with everyone, while visiting our local Fire Dept today in my home town of Mooresville,

  Indiana, I was curious as to what power plants were in the trucks. As formentioned they stated several were

  were 6V's and 8V's. I ask, do you use straight 40 like Delo100 They said no, we use 15w-40. They showed me the

  plate behind the drivers seat and it said, 15w-40. They said they have been using it for years and no problems.

  Question I have, if you can not find any straight 40, would 15w-40 work?


   Steve 5B......,

[Geoff]

Of course 15w-40 works in a 2 cycle Detroit Diesel.  It's not the best, but it will work. Just change your oil at 5K miles instead of 10K.

---Geoff
"82 RTS AZ

[oldmansax]

I've never seen a fire engine with 500K miles on it either.

TOM

[Scott Crosby]

Steve I'm in Avon.  The big Napa store on West Southern St in Indy stocks Shell Rotella 40w on the shelf and Clarke Power on 37 has Detroit Mobil Delvac 40w also in stock.  Both are very close to Mooresville just in case you didn't know. 

[5B Steve]

Steve I'm in Avon.  The big Napa store on West Southern St in Indy stocks Shell Rotella 40w on the shelf and Clarke Power on 37 has Detroit Mobil Delvac 40w also in stock.  Both are very close to Mooresville just in case you didn't know. 

  Scott, Good to know for any bus nuts in our area. O'Riley auto parts in Plainfield will have Delo 100 if you need it.

  I picked up 10 gallions a few weeks back.

  Steve 5B......

[bevans6]

Two fundamental problems with 15W-40 in two stroke Detroits - ash percentage and viscosity breakdown.  Both are problems due to the missing exhaust stroke which cools the piston head on a four stroke engine.  Ash is the metallic byproduct of burnt additives in oil - modern 15W-40 diesel oil has reduced ash to make it work well in modern engines with pollution controls, so from that point of view it's fine.  Viscosity improvers are sued to take a 15W oil and make it act like a 40 oil when hot.  Heat and shearing again breaks down the viscosity improver molecules and after an extended period of use you are left with what is essentially a 15 weight oil.  Hence the recommendation for the straight 40 weight oil - it has no viscosity improvers.  Many true synthetic 15W-40 oils also have no viscosity improvers - they naturally meet both the low temperature 15 weight and the high temperature 40 weight viscosity ratings just as they are, and some even meet the more typical for synthetic 5W-40 ratings.  Many synthetic oils are actually modified normal oil, and still need the viscosity improvers.  Even then, the viscosity improvers are vastly improved compared to 15 or 25 years ago, and if you change your oil regularly the current 15W-40 oils will work fine in your engine, and give improved performance under cold starting conditions.  How often you change your oil may be the key - in service the oil change interval was probably 15K to 25K miles, if we change the oil every 5K miles the use of 15W-40 starts to look better.  Adding a gallon of 15W-40 on the road as a top-up when that's all you can get is fine too, as far as I am concerned.  With that said, I'll use straight 40 weight as long as I can find it...

Brian

[luvrbus]

Ah the oil debate lol 2 fine DD mechanics here run 15/40 in their 92 series I would not use the stuff in a 71 series because of the piston cooling JMO 

I never used 15/40 in my 8v92 either but I wasn't afraid to use it just that I always had plenty of Delvac 1240 on hand I don't know about the 5000 mile oil change with 15/40 back years ago it was done because of TBN because of the high ash content of 15/40

Nowadays with no or hardly any ash in the modern oil like the Delo 400 LE it makes Delo 100 seem like a high ash content oil  lol