Another oil change question

[RedRam1]

I was reading sweek's post regarding whether or not to change his oil before going on vacation. Got me to thinking about a conversation I had with a co-worker a while back, here's the story:



My buddy, and fellow mechanical engineer, used to work for an industrial equipment manufacturer; their product line included aircraft tugs, forklifts, and so forth. Apparently, users often "forget" to change the oil in this type of equipment for years in some cases.



The manufacturer determined that, in order to get the maximum service life out of the equipment, the oil should be changed at regular intervals (sruprise, surprise right?). What is surprising though, is that they found for a high hour piece of equipment that was very, very seriously overdue for an oil change, you were better off not changing the oil. They gathered lot's of data, and did some controlled experiments trying to figure this out.



They discoved that even though your are on borrowed time with a high hour piece of equipment, with ten times more than the max recommended hours on the oil, you could generally get a thousand or so more hours out of it on the old oil. If you changed the oil though, it would suffer a catastrophic failure, almost immediately! Spun main/rod bearings were the usual failure method. When this was reported by customers, they thought it had to be a coincidence, but, as I mentioned, they were able to duplicate it in their testing.



They never did figure it out. The motors had to be seriously neglected worn out p. o. s. 's for this to scenario to talk place, but the company determined that it was indeed detremental to change the oil under the described conditions.



Anyone have any ideas on this topic? I'm a gear head from way back, like most folks here on the boards. I spent nearly all my formative years in garages and machine shops, and can think of no rational explanation for this phenomenon.

 

[illflem]

It's like losing an old friend.

I've never heard this before with motor oil but have heard many times that with an automatic transmission if you don't change the fluid on a regular basis you are better off not changing it at all.

It must be sludge that is filling worn tolerances getting flushed out in the oil change causing gaps.

 

[abledog]

Back in th good old days before high detergent and multi viscosity oils were common there would be a build up of sludge and carbon in the engine over time. If you had an engine with considerable miles and changed to a HD oil the detergent would desolve the buildup and all of a sudden you had an oil burner!



Terry

 

[RedRam1]

I agree that new high detergent oil could dissolve some of the deposits in the ring grooves, and lead to increased oil consumption - although it seems like this would be balanced by the increased viscosity of the new oil.



What they were seeing on the tugs though, was not necessarily increased oil consumption smoking, these rigs were pretty smokey to begin with. Shortly after changing the oil, the motors would experience a catastrophic failure in the bottom end.



I've disassembled lots of motors in my day, and have not seen carbon/sludge deposits on the crank journals and bearing surfaces. I guess there could be some sort of microscopic protective coating built up on these parts, that gets washed off by the fresh detergent in the new oil.

 

[Cobra]

fluid changes

Many years ago a friend of mine had a 63 Ford with nearly 100,000 miles on it. One day he mentioned to me that he never changed the oil but occassionally changed the filter and added oil when needed. I on the other hand had always changed oil and filter like clock work and berated him until he finally did change his oil. The car immediately started blowing out magnificent plumes of blue smoke. The oil consumption was on a par with the fuel consumption. Within a few short months the engine needed overhauled. It really wasn't my doing but he blamed me for it.

 

[A. Brown]

delo and a fleetguard every 3000

 

[RedRam1]

Cobra,



Your buddy with the '63 Ford reminds me of one of my wife's relatives. This guy leases a new GM vehicle every four years. His father-in-law was a GM wheel, and he can get lease deals that are too good to pass up.

He leases vehicles for four years, and usually puts around 80K miles on them... all without changing the oil! He is notoriously "tight", his rationale regarding oil changes is "what's in it for me?" He has leased Tahoes or Suburbans for the past several years, and has never changed the oil in any of them, he does add oil as required, and changes the filter once or twice over the life of the lease. None of the trucks he's leased have begun to smoke, or use an abnormal amount of oil by the time he turns them in.

I've often wondered how the next owners made out, the guy is very meticulous, and maintains the vehicle's appearance extermely well. I'm sure the next buyers think they are getting a well maintained vehicle. It makes me so sick to see him do this, I've been tempted to chang the oil myself!

 

[Gary - K7GLD]

HEH!



Am *I* the ONLY one here who sees the possibility that all these Amsoil lovers in this group who have been trumpeting the "advantages" of the Amsoil in extended oil change intervals, MIGHT just be experiencing what is far more a "natural phenonema" instead of any REAL "superiority" of their beloved brand of engine juice... ?





(THERE, *that* oughta get a good discussion started... )

 

[RichR]

Now,Now

Damn Gary,Things have been kinda quiet latley. :-{}

 

[BFC]

Originally posted by Gary - KJ6Q

HEH!



Am *I* the ONLY one here who sees the possibility that all these Amsoil lovers in this group who have been trumpeting the "advantages" of the Amsoil in extended oil change intervals, MIGHT just be experiencing what is far more a "natural phenonema" instead of any REAL "superiority" of their beloved brand of engine juice... ?





(THERE, *that* oughta get a good discussion started... )

As they say down here "them are fightin' words" LOL

 

[ARARAR]

I heard some what the same thing awhile back, but it was on a local automotive radio talk show, where the guy actually did the math on the savings ($$$) of not changing your oil, but only adding to it and accasionally changing the filter. After 100k miles, with the savings $$$ from not doing regular oil changes, he could just drop a new engine in the car.

 

[klenger]

I doubt that would work with a CTD.

 

[emarsh]

I don't let anyone tell me when to change oil or which oil to use, nor do I try & convert other people when it comes to oil, additives, religion or politics. I got my way and they can keep their way. Argue all you like, oil is the cheapest thing you can buy for your engine, and thats a fact.

 

[pkennedy]

Oil- Synthetic/Petroleum

Ah yes the ongoing debate, I personally use Amsoil and change at 25000km(15000mi) with FG3894 filter. It should be noted though that proper break in is essential, and the CTD is an industrial engine with different materials than your Stock gasser. My 2001 went 25000km on the stock oil and then changed which allows the engine to break in without viscosity enhancers and seats metal surfaces. The next 25k was run with synthetic blend and showed no signs of consumption which is an indication of seating surface health along with an oil sample. The truck has now 77000km and is on its 2nd full synthetic cycle and used only half quart between oil changes, oil sample shows less wear than petroleum ( low iron level ). Tech facts are synthetics flow at lower temps and break down at higher temps= superior metal protection, It should be noted that some driveline manufacturers WILL NOT warranty their rearends or gear boxes without it, eg. NV5600= Dodge 6 spd. Think about it, keeping the truck longer than 5 years or pulling hard don't be cheap the truck wasn't.

 

[pkennedy]

Oil- Synthetic/Petroleum

Ah yes the ongoing debate, I personally use Amsoil and change at 25000km(15000mi) with FG3894 filter. It should be noted though that proper break in is essential, and the CTD is an industrial engine with different materials than your Stock gasser. My 2001 went 25000km on the stock oil and then changed which allows the engine to break in without viscosity enhancers and seats metal surfaces. The next 25k was run with synthetic blend and showed no signs of consumption which is an indication of seating surface health along with an oil sample. The truck has now 77000km and is on its 2nd full synthetic cycle and used only half quart between oil changes, oil sample shows less wear than petroleum ( low iron level ). Tech facts are synthetics flow at lower temps and break down at higher temps= superior metal protection, It should be noted that some driveline manufacturers WILL NOT warranty their rearends or gear boxes without it, eg. NV5600= Dodge 6 spd. Think about it, keeping the truck longer than 5 years or pulling hard don't be cheap the truck wasn't.

 

[RedRam1]

You know, regarding my earlier post about my wife's cousin who never changes his oil, and arar's post about dropping in a new engine at 100K: I got to thinking... for folks who drive gassers for their daily transportatin (no hot-rodders, or heavy hauling/pulling), and who typically trade vehicles at or before 100K miles, it probably makes economic sense to never change the oil.

This goes totally against the grain for me, but after watching my wife's cousin do it for the last 15 years, I have to admit that strictly financially speaking, it's probaboy the way to go.

This guy is on his fourth Tahoe/Suburban, and has never had any oil related problems, heck the truck's still run great, and are not burning oil by the time he turns them in.