hello i have a question referring to mmo being used in high mileage engines. I have a 97 Pontiac gran prix that has 76,000 miles on it and uses 10w30 oil and was wondering when i change the oil should i replace one quart for mmo to oil or should i only use a pint of mmo to oil since it has high mileage?

On high mileage engines, we normally recommend using only 1-pint of Marvel Mystery Oil replacing 1-pint of your regular motor oil.  This allows for a slightly slower clean-up but allows you check for any leaks that have been sealed by sludge and varnish build up.  After using Marvel for the first time, you then can start replacing 1-quart of motor oil with 1-quart of Marvel Mystery Oil.

k thank u i will do that. I was also wondering could i add a pint of mmo to the crankcase now then again when i change the oil or will that harm the motor doing that?, since it stills has the old motor oil in it. The car has been going through a lot of oil and was thinking of running mmo in now and keep leveling off the full mark, till im able to do a oil change. Since its a 3800 v6 with 80000 miles on it i wanted to check before doing so i dont blow the motor up.

I had a 93 Buick LeSabre with a 3800 and started using mmo in the gas/oil at 125K mi with only positive results. It didn’t burn/leak/use any fluids and always started the first time. mmo made it start better and run smoother and helped mpg. the exhaust also had almost no smell. I only got rid of that car because i found a 98 pontiac bonneville with 79K like brand new 4 a price i couldn’t pass up. I use mmo in that car too in the gas and with a good synthetic oil with the same great results.

80k on a 3800 isnt much to worry about as it’s common to see them with over 200k

if mmo doesnt do much with your oil consumption your car might have other issues that a mechanic might need to look at.

thank u very much for your input. I was asking about could i put mmo in the crankcase before doing an oil change so it would already have it in the system without causing problems since its a high mileage engine. Then when i do an oil change put in a another pint or replace one quart of oil for mmo.