50w oil versus 40w

[lostagain]

I see wg4t50 is saying use 50w oil. I've always used 40w. I use Petro-Canada's Dieseltonic, which is specifically made for 2 stroke DD, and is a low ash 40w.

Would a 50w be better?

Why?

Comments?

JC

[luvrbus]

JC, 40w is good for you I used 50w in the summer sometimes never could tell any difference in oil pressure DD has always recommended 50w when the ambient temperature was over 100 you know where I live 100 is spring day lol

Those engines don't have lower end problems because of oil most is caused by water and people not replacing the bearing as a preventive maintenance as recommend by DD keep on using the 40w it won't cause you problems  

I have used 15/40 and 30W in the cold country never caused me a problem with bearings or wear,oil technology has changed so much in the last 10 years the 40w you are using probably has better lubrication qualities than the 50w of 10 or 20 years ago that is my take on it

good luck  

[buswarrior]

If you have a means to pre-heat the engine, and the driver pays the bills, both of which were not prevalent in the coach's earlier intended life...

Once the engine is up to temp, so is the oil.

I run 40 wt year 'round in the coach.

If it was today, yesterday...It would be easy to make up a little inhibit circuit to prevent engine start attempts if the engine was below a certain temp, forcing the hired help to properly pre-heat the engine before trying to start it.

happy coaching!
buswarrior

[wg4t50]

It might educational to reread a later DD Owners Manual, yes at one time year's ago the recommended the 40 wt, however with the 8V-92, 50 wt is recommended, there is much info about this topic, and yes some try to run 15W-40 but for some reason they keep having issues, Amazing.

 Anyway on my 8v-92, ran much higher hp, and 50 wt, never had issues.  The 8V-92 is more tender on the rear main, remember it is the same as the 8V-71 bearings, just much less stress on the 71 series.

This is not something I dreamed up, it came down through the large bus operators who run the 8V-92 engines, they put the word out prior to DD admitting the need for the 50 wt. They had very large issueswith the rear main spinning in the 8V-92, not the 6V-92, as they have less stress on the rear main.

Oil is still cheap insurance.
Sometimes old habits & beliefs are hard to change.

[artvonne]

  My understanding is there is a lot of oil shear at the transfer ports. Multivis has additive to make it perform to its rated ability, but additive isnt oil. In heavy shear the additive falls apart and your left with base oil + sheared up additive = soup. I'm absolutely positive quality plays a large part in keeping a miltivis oil together, but quality is constantly changing. This week this oil is good, next its bad and what was bad is good again.

  MB did a very elaborate test a few years back running engines on dyno's with multi grade and straight weights, straight weight won. Hands down no contest.

  So good quality multi could work okay, if your burning the right stuff, but straight weight will always work okay.

 

[luvrbus]

I have read the latest MTU manual 2010 the same oil spec as always for a 2 stroke only difference now they have 100's of approved oils since the dropping of ash content in engine oils might be a educational read for you

good luck

[Brassman]

I always thought that on a '71 you started with 30w, and if it kept leaking you used 40w, and if it kept leaking you used 50w.  

[buswarrior]

Lots of us on here with first hand experience, coach arrived in our possession with multi-weight and the oil was going somewhere, at quite a rate, after changing the oil to straight 40wt, the oil consumption changed noticeably for the better.

And most of us have read the older stuff on the Tejas site...?

http://www.tejascoach.com/

In summary, lighter oil (which is what a multi-weight is) is too easily squeezed out of bearing surfaces due to the loads in a two stroke, allowing metal to metal contact. The oil is supposed to prevent metal to metal contact via a thin film.

And that, folks, is the path to ruin.

Luvrbus, do you have a link to that new stuff from MTU?

For the congregation, on the new stuff, the emissions equipment dictates low ash in engine oil, as the ash is not good for the Diesel Particulate Filter or DPF in new vehicles, same as the lead would ruin the catalytic converter in our cars way back in the 70's, which brought about unleaded gasoline. In the last few years, heavy duty diesel engine oil has been dramatically changed to accommodate this low ash requirement.

Detroit Diesel has dictated that the engine oil for a Detroit 2 stroke must have low ash content, as higher ash found in many previous generation oils, was harmful and allowed wear. And, from history, there was a short time that Detroit said multi-weight was ok, and then rescinded that recommendation.

Be sure you are not taking action on out of date recommendations!

happy coaching!
buswarrior

[Ed Hackenbruch]

I always thought that on a '71 you started with 30w, and if it kept leaking you used 40w, and if it kept leaking you used 50w. 

And when you get up to 90 wt. it is time for a rebuild.

[Van]

Aww c'mon guy's... oil is oil isn't it? or was that anti freeze? I dunno! 

[buswarrior]

For the uninitiated, Van was joking....?

The formulation of both the oil for your personal conveyance, and the oils for heavy diesels have changed dramatically over the years.

And a 2 stroke Detroit has specific requirements, that many modern oils may not meet.

happy coaching!
buswarrior

[Van]

 

[PCC]

50 w  -  40 w  -  I can see better with a good 60 w.

We talking light bulbs?

My 8V92 runs with 40w and never seems to lose much even after 10,000 miles.

I think I will stay with what works.

But to know that, in a pinch, I might be able to use 50w (or 90w !!!) to top up is a good thing.

[wg4t50]

Its all about the rear main bearing, RV use is light duty, low mileage, but in the commercail bus fleets that are still using the 8V-92, are using the 50 wt.  Only cuz they got educated.
As usual, do what makes you happy.
Cheers

[Barn Owl]

My bus came with 30wt. I switched to 40wt. I have been running 50wt for two years. I cannot tell the difference other than the 50wt leaks out slower.