I have a '69 bonneville engine. I read that the main engine oil is located beneath the seat and that there should be a way to measure how full it should be. There is oil in it, I can see, however, I can see no marks or dipstick or lines or anything that would say I'm low. On a side note, does this engine share with the primary oil? I read that somewhere but I'm not sure. Any help would be appreciated.