[Ron R]

Spoke to a guy who makes a living of transporting strange objects.
He told me the following story
Uses 70-series LC's for this pupose. Trailers are in the 1600-4000 kg's (approx 3500 to 8500 lbs) range. Drives a total of several 100.000 k's a year (several cruisers/drivers).
Some time ago he decided to switch to full synth engine oil for one of his newer LC's after having it run-in for about 30.000 k's. Raised the oil-change intervals to 20.000 ks. After some time he found that engine performance dropped noticably around 18.000 k's. After oil-change everything was back to normal ...until 16.000 k's. Again oilchange all fine until 14.000 k. This he could compare because at that time he regularly had to do the same kind of load the same route that has a fairly steep incline at a certain point.
Not understanding this and asking around he was advised to switch back to dino and lo and behold after the second oilchange (at 10.000 k's) everything was back to normal!

Anybody ever heard a story like this. This because I have been thinking switching to full synth.

[83bj60]

Originally Posted by Ron R

Spoke to a guy who makes a living of transporting strange objects.
He told me the following story
Uses 70-series LC's for this pupose. Trailers are in the 1600-4000 kg's (approx 3500 to 8500 lbs) range. Drives a total of several 100.000 k's a year (several cruisers/drivers).
Some time ago he decided to switch to full synth engine oil for one of his newer LC's after having it run-in for about 30.000 k's. Raised the oil-change intervals to 20.000 ks. After some time he found that engine performance dropped noticably around 18.000 k's. After oil-change everything was back to normal ...until 16.000 k's. Again oilchange all fine until 14.000 k. This he could compare because at that time he regularly had to do the same kind of load the same route that has a fairly steep incline at a certain point.
Not understanding this and asking around he was advised to switch back to dino and lo and behold after the second oilchange (at 10.000 k's) everything was back to normal!

Anybody ever heard a story like this. This because I have been thinking switching to full synth.

This is worrisome, loss of power at 18,000, then 14,000, then 10,000... what engine is this 70 series running? What's its mileage? Is he burning oil? How is the injection pump? Have the injectors been serviced? What brand and grade of synthetic is he using? What are the temperature conditions?

With the kind of loads he's carrying, I find the mileage bewteen oil changes frankly excessive. That would definitely be classified under 'sever service' and require more frequent oil changes, not less...

[HZJ60 Guy]

IF there is a problem that using synthetic brings to the surface, (it is VERY slick and often causes leaks in old engines) then that's a problem you NEEDED to fix in the first place. There is nothing bad about synthetic oil.... Save maybe the cost in comparrison to dyno oil. It has been being run in old and new diesel engines around here for twenty years!

[Lantec]

20,000kms?? Whoa. That's pretty long for an oil change. I change my oil around 7,500km-8,000km and i'm running synthetic

[Martin White]

I don't buy it. I've never seen a creditable study anywhere that showed a performance loss on synthetic for a modern engine. Some leaking, yes, but performance loss suggests something else is going on here.

[denis]

what viscosity ?

[Ron R]

Will try to answer some of the questions, as I don't know all the details.
The engine is a HZ1, no strange things, just standard.
At the moment it has about 190.000 k's and doing well. I saw the rig myself. It looks well maintained and the engine doesn't leak at all.
Temperatures here in western Europe are in general moderate. We don't have excessive low or high temps and in this region we don't have any mountains. At best it's hilly.
The guy told me he had the IP and injectors checked because that was the first thing he thought of. Except for one of the injectors everything was fine. After repair problem persisted, then he went to dino.
I agree fully about 20.000 k's interval being to long. I would go for 7.500 k's as well. But he said he allways maintained his rigs like this and never had a problem before.
Because the story sounded strange I've put it here, but having said that, there is no reason he would lie about it. He doesn't sell any stuff to me, nor am I related to him in any way.
All I know about synthetics is that many use them. And with good results in general.
But asking around can shed some light every now and then