The tag on the side says:

115 Volt
6 HP
15 Amp
Doesnt say anything about a max breaker size.

And it is a 30 gallon.

Before go any further.

What gauge wire is that circuit on?
What is the cut off pressure of the compressor?

Be careful with this question. Be sure to check the entire circuit. Too often I've heard of electricians wiring a 15A circuit using some 12ga. Not illegal but foolish if you as me. It fools less competent home owners and even seasoned electricians later when they mistakenly assume the entire circuit is wired with 12ga and choose to upsize the OCPD to 20A.

A competent electrician would never assume anything.

Bob

Edit: Correct me if I'm wrong but is it still allowed to use 14ga. pigtails to supply 15A receptacles on a 20A branch circuit?

Bob, I believe that depends on two things.
One is your interpretation of the tap rule and the other is if it's a dedicated circuit or not.

Personally I don't like it, it's just trouble waiting to happen.

I belive it is 12ga but Im not 100% sure. There is literaly 2' of wire between the outlet and fuse box. The compessor shuts off at 135psi just as it should. I drained the oil and replaced with ATF today, seemed to be better but time will tell.

Well I replaced the oil with ATF and it is deffinetly better but it still trips the breaker once in a while. Is is possible to make this into a 30amp circuit? What would be involve in doing this right? Like I said I have access to the entire ciruit.

"I belive it is 12ga but Im not 100% sure."

If theres only 2' of wire between the fuse box and receptacle why not take a look and tell us what it is?

If its 14 gauge on a 20 amp breaker thats not safe. The idea behind the breaker size is to protect the wire. It could also be the root of your problem.

If you run 10 copper AWG off the breaker or fuse panel and use a 30 amp breaker. That wire is protected by an appropriate size breaker. What gauge wire is on the compressor's cord? If its not 10 then you you can't use a 30 amp breaker.

The 20 amp breaker on 12 copper AWG should be sufficient for your compressor. Your compressor is tripping a 20 amp breaker when getting up to 135 psi. Why is that? Thats what you should be figuring out. It could be as simple as a cheap 25 cent receptacle or it could be the motor is getting hot or just wore out. Right now the 20 amp breaker intended to protect 12 gauge wire might be protecting the motor. Protecting the device isn't the breakers intention, as said it protects the wire. Putting the compressor with a suspect motor on a 30 amp circuit could toast the motor. If your going to treat the symptom then turning the cut off pressure down would be way better then a 30 amp breaker.

Or a guy could put a bigger pulley on the compressor (or smaller on the motor) to lessen the load on the motor. It may fill very slightly slower but with less load on the motor with the same output PSI.

I have the same size compressor, I believe. When my house was built, the electrican mounted two GFI outlet boxes, right near the breaker box in the garage. One towards the top of the breaker panel, the other near the bottom. The builders used them when building the house.

During the winter, my compressor will trip the lower 2-outlet box, all the time, during cold weather. So, last year, for giggles, I tried plugging it into the upper GFI outlet box. It has never tripped a breaker during winter yet.

Maybe a weak breaker? I don't know.

Heat rises. Maybe the top receptacle is warmer.

Bob

6HP? No such thing. 15amp, 1 to 1/12 HP max runs on 15amp breaker.

A "True" 5 HP motor draws 22amps, 220/230volt, single phase.

Compressor MFG's play games. "Peak" hp is the killer. Motors are rated at "Peak hp, No load, at start up". (Rated at 4 times the name plate, from dead stop to start(the reason a breaker will not trip is it is time delay, amps are huge for a millasecond to start the motor)) I am speaking of the "big box store compressors" (and vacuums). Ha, wife has a 12 hp Hoover...(Max single phase,230 volt hp motor can run is 10hp, she runs it on a 15 amp 110 volt shared circut with the microwave, and kitchen lights...

Ratings in compressors are not spot on.

Brandt, how you been.
I was hoping you'd find this thread.
I figured the same thing on the 6 hp rating.
Brandt is a compressor guru btw.
So whats your take on the tripping breaker?

Sorry I forgot to add, it is a 6hp peak and 1 1/2hp the rest of the time.