I stick with the Sunnen Honing Oils available from Guspro in Chatham Ontario.
I have tried many other brands over the years, never seemed to work as well as the Sunnen Oil for various reasons.
Sunnen seem to have a Superior additive pkg contained in their Oil that works the best with their stones, promotes good stone performance(cutting), especially with the finer JHU820 and final plateau Brush wipe finishes(no comparison) Sunnen Oil is more expensive, however IMO, works BEST !
My second choice for a good all around Honing Oil using JHU525 & 625 Stones mainly, would be the Honing Oil available from C & C Valves in Edmonton or Missisauga Ont.
I don't know the product name, just ask Chris @ C & C for it.
It is FAR Cheaper than the Sunnen Product, and works pretty well with just the Addition of a 5 Gallon pail of the Sunnen Additive Man C or Man 5 ? I forget ?
Just make sure when going to Final Hone finishes, to burnish the Stones more frequently.
I really dont think that varsol would be a good ised. It is much "thinner" than mineral oil plus it evaporates. You could call SUnnen to make certain, but I just dont think that will work.
Personally, even though it is very expensive, I would stick with the Sunnen MAN 845 oil and nothing else. Maybe the concentrate but only if you use actual mineral oil.
If you keep the filters changed and use some good filter paper in the bottom of the machine under the blocks, it will probably last at least a few years before it needs changing. Its probably been at least three years since I have changed mine doing probably 2-3 blocks a week ? I do have to add it occasionally to make up for what stays with the blocks, but thats it.
Good point... I don't have any problem with 845 except access. Mineral oil is impossible! The man-c is available. Sunnen says the first choice is mineral oil to mix it with! Not much chance. So the obvious option is a cheap honing oil. Sunnen suggests and alternative mix would be Faxam 10 from ESSO. I haven't looked into that yet. When someone suggested varsol, I liked that because I have a couple of drums. But evaporation would be a concern.
I know it's a tough $$ to swallow,
you'll never be sorry if you just bite the bullet and get the Sunnen Oil from Guspro ? Especially if you are using your Machine for Boring with the Diamonds ?
To repeat what BillK said,
get a good quality clothe in the bottom to act as a "Pre"-Filter and it will last a long time.
I don't think you will be happy with Varsol, Evaporation & Fumes.
Anybody whose done an Oil Change & Filters on their Machines know the "why" behing Boring & Honing costs Money !
I've gone back to Manual Boring after Sonic Testing the Blocks to within .005" of final for that reason, saves plugging up my Filters with debree from the Diamonds and Stones.
I just Hone the Final .005" these days, then sit my Blocks to drain in Pans, to recover as much of the precious Oil as possible, LOL !
If you need a Barrell of the Sunnen Oil, let me know, I have an Account and would be glad to bring in a Barrell for you at cost. You would need to pick it up from my shop here in Jaffray, 1 hour away ?