I've read here on one of the posts that it doesn't matter when it comes to using synthetic oils in a diesel engine. I've read elsewhere on a manufactures sight that they have obtained oil drain intervals of never having to change the synthetic oils. Now to do that the manufacturer does state regular oil analysis in conjunction with a oil scrubber filter or by-pass filter that can remove sub-micro sizes of dirt particulate. The standard filter being used is also one designed by the manufacturer. I realize by changing the filters and through normal consumption of oil during operations that fresh oil will be regularly introduced into the system, however that amount in ratio to the sumps capacity in a diesel isn't all that large. Why such a divergence in opinion when it comes to synthetic oils in a diesel applications.

thanks for the comments

Can't perfectly explain the divergent opinions except to say that some folks are stubborn when it comes to change.

Synthetics have been around long enough to prove themselves enough. They don't break down at temperatures that turn conventional motor oils into sludge. That reason alone is why EVERY turbocharged motor or any motor that sees hard work should be using them.

Filtration is quite important, as you point out.

Seems to me that the people talking against synthetics are doing so largely with empiric observation or plain old 'wives' tales'.

I use sythetics in every engine I own, and every engine that I want to keep.

In the trucking industry they try to squeeze every last dollar out of everything they own. When trying to save money the first place all trucking companies go to is the maintenance departments.

Some of my trucking company friends have "oil spinners" (centrifuge) and "oil drippers" (burners) and "automatic greasers" as there "Holy Grail" for extending maintenance, thus saving them money.

Extending oil change intervals to acceptable levels will save money and natural resources this should be the goal. The thinking then becomes "well it went 100,000 miles lets go for 125,000 miles" and so on.

We have on this site a "Rusty Oil Can Man" who knows about these things. I quote from this man "Oil Is Cheaper Then Metal" seems to ring true.

Now reality, extended drain intervals are here to stay. People will push there rigs to sick intervals just to prove it can be done. The fact is these people are all over there motor sending oil samples out all of the time. The analysis won't come back for days and by that time major damage could result.

Lets say there's nothing wrong with the oil. Who's looking at the other stuff that wears out if no ones looking around the motor? Some of these companies I work for seem to have a lot of road breakdowns for some of the stupidest things.

Check with the oil manufactures and the engine builders who invest millions of dollars and are pushed by the "let's extend" crowd to see where the real world is at on this. Ask them about extended drain intervals. Don't go off of some websites claim that you never have to change the oil. Things wear out, packages get depleted!

Do you own a fleet of trucks? What is "your" motivation for extending? How good is your maintenance program?

Bill N.Y.

I don't have a lot of experience with diesels but gas powered engines I do. I use synthetics in all of my gas engines but in diesels I have I use Mobil Delvac oil and change at regular intervals and not long intervals either.

When BMW went to "life time" oil in their transmissions, it was and is a disaster, the transmission fail with great regularity and almost predictably around 100K miles. They have also gone to "extended" oil change intervals on the engines to 15K miles or so with synthetic oils. Say what you want about synthetic oil not breaking down but the sludge build up in these BMW serviced engines is unbelievable. Does BMW care? Sure they do, if the engines and transmissions last a long time, you won't buy a new vehicle as soon! BMW's definition of "life time" is "end of warranty"! I have been wrenchin' on BMWs for over 30 years and don't like what I see there and I know they are not alone in their proceedures and processes.

I change oil at 7500 intervals using synthetic oils in gas engines and I change at or around 5000 in the road going diesels, for the stationary and tractor diesels I change oil every year at a minimum or more often if the use conditions are dusty areas or greater then 100 hours per year.

Is this a recommendation? No, it is just what I have found to work well for my use and applications and the engines I have, have gone a long time, when I open them up, they are very clean. I do an oil analysis on the Barth just to be able to have a precursor to reduce the chances of being caught with a major melt down while on the road.

I am sure this debate will continue as long as there are choices available.

quote:

Originally posted by MWrench:
I use synthetics in all of my gas engines........... I change oil at 7500 intervals using synthetic oils in gas engines

Me too. Or annually if less mileage.

What brand of oil filters are you guys using when changing at 7500?

I use OE filters on my gas engines (cars, truck) and either Wix or Cummins supplied filters on the Barth. Tractors I use Wix.

No endorsement but haven't had any issue. I use the labs in Illinois for oil analysis, I get the kit from my parts supply house.

First, "synthetics" aren't really "synthetic" but rather "synthesized". Base stocks are processed and synthesized to rmove impurities and to provide an homogenous product.

Second, I, at least, have never said the using synthetic oils in a diesel doesn't matter. What I have said is that using synthetics in diesels is a waste of money. If one realizes the benefits of synthetics in diesel crankcases, one has over stretched the drain interval.

While the statement that synthetics don't break down at temperatures that would "destroy" conventional oils is partially true, it's disingenious. If motor oils are subjected to that kind of temperature, the engine has other, far greater issues, and base stock deterioration is among the lesser concerns.

To a motor oils base stock is blended an additive package which provides anti-scuff, anti-oxidant, EP, anti-foam, anti-acid, etc.

It isn't the oil base stock that goes bad, it's the additive package that gets depleted. A good portion of that depletion comes in neutralizing byproducts of combustion.

Byproducts of combustion in a diesel are far more plentiful and nasty that those in a gaso engine.

Diesel motor oil is discarded when the additive package is depleted, not when the base stock is "worn out". This is why engines with larger (14-32+qts.) can go longer between changes.

The hardest condition that motor oil has to endure is cold starts. Cold starts followed by short trips or extended idling is the worst operating condition. Warm idling is much less deleterious.

OTR trucks are the least hard on motor oils; local cartage is about the worst.

What MWrench noted are classic symptoms of over extension of lubricants. When the base stock is depleted, the long-term result is in fact damage to the base stock (sludge), and damage to the victimized machinery (varnish, carbonaceous deposits, and worse).

I use synthetic in transmissions, differentials, and power steering, and in my gaso car engine. In the Barth and my diesel van, Rotella T 15W/40. Mobil Delvac or Kendall Super DIII are the only other motor oils I'd consider.

I also installed a Mag-Hytec transmission pan (GM4L80E) and diffy (Dana 80) cover in the Barth. The tranny pan increases capacity by about 45%; the diffy cover by about the same. Both are cast aluminum and provide far better cooling than the steel pieces replaced.

As far as oil analysis is concerned, there are issues with monitoring change intervals:

1. Tests run
2. Accuracy of the tests
3. Sampling procedures
4. Time delay
5. Interpretation of the results

Finally, some forum members may not be aware that I was for years a fuels and lubricants field angineer and product applications engineer for a major oil company, and also spent over 20 years in the Naval Reserve as one of two of the Navy's Fuels and Lubricants Technical Officers, so I at least understand the basics. I don't resist change; I embrace it only when it's for the better.

Rusty, please do NOT think that any comment I made was directed at you.

I was speaking in general terms about some of the resistant attitudes I have personally heard from people regarding the use of synthetics.

Sorry if that was unclear.

Windsor, I took nothing personally, nor do I attribute the statements to you personally, either, rather that you were conveying one you had heard.

As you have illuminated, there's a great deal of misapprehension, disinformation, and Old Wives' Tales out there.

What I try to do on this forum is to relay some of the knowledge the oil company and the Navy infused in me at considerable expense...

quote:

Originally posted by Bill Stevson:
What brand of oil filters are you guys using when changing at 7500?

Try this thread, I like using Wix/Napa on my personal vehicles. I also opt for the larger 2 quart filters.

Bill N.Y.

Only Wix/NAPA go into my diesels. I'm more particualr about that than my brands of lipstick and mascara....

But I change the 1T Ford 6.9L diesel van at 4K (10 qts) and the Barth (7 qts) at 3K.