The oil hose is particularly tough with an inside diameter of 7/16", The "push on" fittings I have for the oil cooler & thermostat are AN-8 that suit 1/2" ID hose. Even with hose lube & soaking the hose in boiling water, I was able to advance the hose about one millimetre at each "push". It took forever to install just one fitting & I'm sure I almost burst a vein somewhere. Anyway, one down & 5 to go!
