Hello, I have a older Okuma Ls manual machine that i need a little help with. I believe they actually call it a LS-540mm by 1500mm. Im also not sure but i think its a 1964 model with a serial number of LS 4109-10352 but if anybody knows how to deciper the serial number that would be cool. I was looking to change the oil in it from when i got it but when i called around all i got was that it took 2.5 gallons of #90 turbine oil. When i called some oil distributors they didn't know what to say either and looked on the net all i coud find is that #90 turbine oil came in different viscosities. I looked at the old oil but its kind of dark to tell what it actually is or how thick it should be. All i have is the electrical manual for the machine so if somebody has a actual manual with some specs or done this before i would greatly appreciate it. Thanks, Andrew.