Havoline Xpress Lube

I had bought the oil and filter to change the oil in my truck. But my back went out so I was willing to pay for the labor. When I got there the girl said it was going to be 25 bucks and I said fine. Mind you they have a coupon online for 29.99 complete oil change. Then this RUDE guy walks over and said no it will be 50 bucks. I asked him why, and he said because it is diesel engine. Mind you the labor is the same as any other car. Pull the plug let the oil drain change the filter, and refill oil. I will never go back to this place, I think they're the kind of place that will sell unneeded services.