I need to add 3oz of product per quart of oil; my question is: since my car's oil capacity is 4.25 quarts do I add auto-rx (entire bottle of 12oz) to the 4.25 quarts of oil, or pour the product first, then oil (to total 4.25 quarts)? I hope my question is clear, I just don't know if I risk damage by having more than the capacity. Thanks for your help.
We get similar questions all the time. Personally, this is how I would proceed. All engine sumps have a little wiggle room from the full dipstick fill and what would become a dangerous overfill situation. In your case I am assuming that you are getting prepared to running a cleaning application, installing Auto-Rx into your host motor oil. I would first add 4 quarts of motor oil into the drained sump. I will also assume a fresh oil filter has been installed. I would next add a full 12 fluid ounce bottle of Auto-Rx to the sump. Next I would start the engine and allow to run for 3 to 5 minutes to have the Auto-Rx disperse into the host motor oil. Now shut the engine down and allow 5 minutes for the oil that was pumped up to the top end of the motor drain back down so that you may take an accurate reading on the dip stick. Also by running the engine for the 3 to 5 minutes you have also filled the oil filter with oil, which will remain in there due to anti-drainback valves in the oil filter in most cars. Now that the oil has had a chance to drain back to the sump, take your dipstick reading and adjust up to the full mark if needed.
There is no real wrong way to accomplish adding Auto-Rx to the sump. You could have added it first, then the oil. Also in gasoline engines there is always enough wiggle room to install Auto-Rx into a crankcase that is already at the full mark. A full bottle of Auto-Rx really only represents roughly the volume of 1/3 of a quart oil. As long as you have not overfilled the sump with oil to start with, adding the correct amount of Auto-RX will not adversely cause an overfill in a gas motor. Please read on if you are applying to a diesel.
In diesel engines, please be advised that it is never a good idea to overfill the crankcase at all. Never exceed the full mark. This can lead to a runaway diesel. In short a runaway diesel occurs when the motor sucks up the oil from an overfilled crankcase up through the intake system and the motor uses the oil as fuel. In many cases this can lead to uncontrollable revving of the motor, which is very dangerous out on the road. In a runaway diesel the motor is likely to be severely damaged.
