Mike, I hope you don't mind me asking, but why do you want oil for your pump?
"Horton"

Just checking it out before the season I think the oil level is low. Thought It might be good to change it with some new. The pump is an older on & does have a oil plug for filling.

Ah so! any non-toxic mineral oil should do, I would think, Mike.
Can't say I have ever seen a oil filler plug that was removable, on the typical [pond type] oil filled pumps.
They are more common on industrial pump motors.
Are the seals leaking a bit and you are losing oil?
Try the link below for a source for mineral oil.
"Horton"

Here is a link that might be useful: Mineral Oil

Ya. I see a little oil film. Not bad. Probably from setting all winter in water. Pump has a little plug in the front for filling. I suppose I wasn't supposed to take it out because of the warranty. But the warranty is off after one year & the pump is 5 years old. I say a prayre every morning when I get up to make it keep running. If anyone else is reading this I also found one the pump before starting this season,a loose nut on the impeller & loose bolts on the case. Good thing to check each year. Mike

Mike you have an Aquascapes pump that was made by Tsurumi. If it pumps about 3000 gph it is a Tsurumi model OMU2. They recommend checking and changing the oil once a year and that is why the plug is there.
Mike

Mineral oil is a good lubricant for guts, but unsuited for motors and engines.

Lightweight marine engine oil is available in a biodegradable, non-toxic formula. Check your local marine supply shop. If you have none, do a websearch.

Birdwidow, I am assuming that in this case the oil is used as a coolant for the electric motor windings not as a lubricant? Mineral oil is commonly used for that purpose.
I maybe away off course here and Mike Ill, could correct me as to the purpose of the oil's use, in this case.

I have a continuous duty industrial sump pump that I use to drain out my bottom drain sump. It has a filler plug and uses mineral oil as a motor coolant. It also leaks a drop or two of oil when in use.
"Horton"

Yes it is used only as a coolant.
Mike

Thanks for the info. The pump is a 4500GPH. Mineral oil it is! Mike

Mike, probably the safest thing to do is just buy yourself a new pump. Having the pump fail during the summer could cause you to lose some of your fish?

I had a few pumps that lost a little oil so I kept them as back ups and bought new pumps to replace them.

Now I use pumps without oil so that is even better.

FYI. I found my mineral oil at Walmart. On the bottom shelf by the baby oils. I dumped the old oil out & found more water than oil. Cleaned & refilled. Runs like a charm. For how long don't know. Thanks for your help. Mike

the following link tells ALL about the Aquascape line and oil usage

Here is a link that might be useful: Oil that Pumppy

natteringinny, interesting and relevant information.
Thanks for posting the link.
"Horton"

Yes a very interesting and misleading link. The comments are the best and they were talking about the 3000 pump which one of the better pumps and they were still having all kinds of problems.
Mike

Mike. Why don't you get over yourself? Sometimes I think you actually believe that you are the supreme expert on EVERYTHING. You ain't even close.

Haven't been on here for a while as you can see. I have had my Aquascape SFA 4500 pump now for 7 years. Was debating if I should get another pump or have it repaired(noisy & leaking). Bearings & seals were bad. Had new bearings put in at local bearing store. Purchased new seals from Bergman Specialties in Michigan. & installed. Total cost around $150.00 Pump runs like new. No noise. Works great. This pump has a oil chamber for the seals. Use mineral oil in chamber. Hope to get another 7 years if I'm lucky. Happy ponding, Mike

I have a Flotec 1/6 hp pump and accidentally spilled the oil, started doing research for a replacement I could use today(Sunday). No local stores carry dielectric oil so I tried to find an alternative. Found this link for seed oils(Rapeseed, for example)

http://www.transform.ru/articles/pdf/SIGRE/d1-202.pdf

The research seems to say cooking or massage oils might work.