I've seen where some are using a 10w oil for hydraulic oil. Any issues using the 10w in a Cat 315cl ( 2006) ?
Nope. We've been running Cat spec 10W hydro in all our equipment for 20 years.
Only 10w cat oil ? We have a exxon dealer with 10w
Apart from some specific exceptions (and your 315C is not one of them) Cat hydraulic systems generally specify Cat Hydo Advanced SAE10W oil or a "commerical SAE10W hydraulic oil". Sometimes the change period will be cut, e.g. 4000 hours using Cat HYDO oil, 2000 hours using a commercial oil. You can use any good-quality branded SAE10W (or ISO32 AW) hydraulic oil. IMO Exxon would fall into that category. Tip: If the supplier has an SAE 10W oil that meets Cat TO-4 specification and if it is cheaper than their 10W hydraulic oil, buy that. Your machine hydraulic system does not require the TO-4 oil, but neither will the TO-4 additive package do it any harm. We used TO-4 oil in all our small/medium Cat equipment hydraulic systems.
I work for a CAT dealer and that's all we use on every machine. Its required for us to keep in compliance
Obviously, SAE and ISO use two different scales to measure viscosity. SAE 10W is equivalent to ISO 32, SAE 20 is equivalent to ISO 46 and 68, and SAE 30 is equivalent to ISO 100. As you can see, there is a bit of a difference between ISO 68 and SAE 30. The viscosity of the fluid largely determines the oil temperatures within which the hydraulic system can safely operate. So if you use oil with too high a viscosity for the conditions in which the machine must operate, the oil won’t flow properly or lubricate adequately during a cold start. Likewise, if you use oil with too low a viscosity for the conditions, it won’t maintain the required minimum viscosity, and therefore adequate lubrication, on the hottest days of the year. In fact in Vietnam we often use ISO 68 hydraulic oil for construction machines because of the weather in Vietnam; especially in the southern, the outdoor temperature is often very hot https://www.machinerylubrication.com/Read/29715/hydraulic-engine-oils