Omega,
Your problem may not be the oil at all. I would first look at the pump. Check the coupling or pump shaft to see if it is damaged or slipping. Also check the pump to see if it has a bad bearing. Next, check the pump pressure to see that your relief valve is set correctly. Next, check your engine rpms. If the engine is actually working at higher rpms, the pump can be trying to put out more flow than it is rated at. This will cause a noise in your system and can also give indications of air or cavitation due to fluid velocity being too high. Once these are checked, then I would continue to troubleshoot the system from the pump out to the cylinders. Look for leaks, cracked fittings, crimped or damaged lines, etc. This should give you a good start. You can go to
www.ihd-usa.com to purchase a fluid power data book. The cost is $1.00 per copy. They have a fairly good troubleshooting guide in the book. Good luck.
