Can using a synthetic oil be a problem?

[Deltona]

I have a 1987 Lister Petter in a dumper, they specify a non synthetic engine oil. Would it cause a problem to put a semi synthetic in?
It's just easier to find these days, I've probably already got some on the shelf somewhere.

 

[Barkleymut]

Had to google Lister Petter, i know in the past semi syns were 80% conventional. So you would be 80% following the manufacturers recommendation. Maybe you could email the company and see if they now recommend a different oil?

 

[MRC01]

In most applications, synthetics are compatible & miscible with dino-juice/mineral oil of the same viscosity and type. However, there are exceptions to this general rule. For example, aviation piston engines, where Mobil AV1 (synthetic oil) couldn't keep lead (from leaded gasoline) in suspension, ruining engines with lead sludge deposits.
So, I would take @Barkleymut 's advice and ask the company.

 

[Deltona]

It's so old I didn't know the makers still existed, but I see they do! You're right, I could contact them, but I doubt their knowledge base goes back so far, nor will they have done any R&D or have any evidence of what a modern oil would do to an older engine. Still might ring them though, you never know who will pick up the phone.
I'm really not sure myself hence the question, I mean (aside from your aviation example) what could happen? I was pondering over it being too slippery and effecting the bores (glaze) perhaps, but only a guess. These engines spend a lot of time on tickover or at very low speeds of course.

Since I posted an owners handbook has arrived so I now know an oil grade, I've also got some on the shelf and it's easily available so will probably stay with mineral and not tempt fate, it is a very old and battered machine anyhow and I doubt there is much to be gained from a synthetic as this age.

Thanks for your posts, they got me thinking.

 

[dlundblad]

1987 and they don’t want a synthetic? Is the year a typo?

Is a Lister Petter just a brand of diesel engine? Looks like Ditch Witch used them.

Also, what is a dumper? I have a photo of my Shepherd doing one, but I don’t think that’s the same thing.

 

[wpod]

Use a HDEO like Shell Rotella or Chevron or Castrol, Mobil in the recommended viscosity.

 

[kschachn]

In most applications, synthetics are compatible & miscible with dino-juice/mineral oil of the same viscosity and type. However, there are exceptions to this general rule. For example, aviation piston engines, where Mobil AV1 (synthetic oil) couldn't keep lead (from leaded gasoline) in suspension, ruining engines with lead sludge deposits.
So, I would take @Barkleymut 's advice and ask the company.

But that was a predominately or majority PAO whereas most synthetics today are Group III base stocks, which are essentially chemically identical to non-synthetic stocks.