High mileage - initial MMO or Sea foam treatment?

1999 5.3L Z71 4x4. 247k miles. Coming up on an oil change and I've recently noticed a click in the engine on initial start up which continues until warm up. I'm guessing a lifter issue. Oil pressure seems slow to come up until temp is reached as well... Is there any major concern with an initial treatment of Marvel Mystery Oil or Sea foam at such high mileage? Should I plan on an early oil change next time in case things end up getting "too clean"? Am I asking for trouble by trying this on such an old engine for the first time?

1999 5.3L Z71 4x4. 247k miles. Coming up on an oil change and I've recently noticed a click in the engine on initial start up which continues until warm up. I'm guessing a lifter issue. Oil pressure seems slow to come up until temp is reached as well... Is there any major concern with an initial treatment of Marvel Mystery Oil or Sea foam at such high mileage? Should I plan on an early oil change next time in case things end up getting "too clean"? Am I asking for trouble by trying this on such an old engine for the first time?

I have used marvel oil on high mileage vehicles ..my 1983 had 380,ooomi when I sold it...the engine was never touched...no leaks...even the valve covers...used dino oil every 3,ooomi ...no fram oil filters...


on my current vehicles I use this marvel in the oil and fuel. this used at the proper amounts does clean the engine of deposits..also it cleans and lubricates the fuel system and the compression rings...

In the engine oil 1oz/qt of oil..in the fuel 1 oz. / 10 gallons ....

use a high quality oil filter..no fram's...dino oil is good for about 3-4,ooomi.
or about 4 months...

since you have high mileage in this engine I would not recommend synthetic oil toooo late now...damage is done..


10-30wt oil is the highest viscosity I would use..slow rise in pressure could indicate oil pump issues or the screen is gooped up with sludge...

If you have sludge because of delayed oil changes you must be careful to watch the oil condition ..as the oil turns black you must change oil and filter....the marvel will breakdown this sludge...so maybe after a few hundred miles you may have to change oil/ filter..repeat until it stays clean..eventually it will ...

sea foam is a product some love or hate...I have never used it ...since the marvel does it all and why play games and take a chance...

I've been using this product for decades...

Thanks, JC.. I was wondering if I had to be concerned with MMO having the same "solvent" effects like running biodiesel through an older dino system. I'll plan on doing a couple of extra changes every few hundred miles for the next month or so. I'm guessing the same thing should be planned for with fuel filters as well...

Thanks, JC.. I was wondering if I had to be concerned with MMO having the same "solvent" effects like running biodiesel through an older dino system. I'll plan on doing a couple of extra changes every few hundred miles for the next month or so. I'm guessing the same thing should be planned for with fuel filters as well...


I would watch the oil color. when it gets very dark change oil/filter...

you may not have alot of sludge/ carbon deposits...

the fuel system is in need of a filter change if the filter has more than 30,ooomi..replacing the filter reduces pump stress. the marvel oil lubes and cleans the system. reduces any corrosion issues as well..

just use this product with the amounts I stated no more..after a few hundred miles you will see faster cold start and the engine will quiet down..you may also find it idles smoother...

post back what happened good luck.

I have seen in a few topics where people talk about this marvel oil, Few questions about it, where do i get it, and 140,000 miles on a 6.0L is it too late to use it?

I have seen in a few topics where people talk about this marvel oil, Few questions about it, where do i get it, and 140,000 miles on a 6.0L is it too late to use it?

auto zone advanced auto and many other auto supply stores...this product has been around for a very long time...


any engine can use this product ...the problem comes when it is used in amounts greater than I have recommended...more is not better...

if you have lifter noises, sludge, carbon deposits this product slowly over time will improve engine performance...

also when storing your engines over the off season adding to the cylinders this product and rotating the engine by hand , plugs removed, will insure a safe storage...

OK jc... Double checking.... MMO bottle says 4 oz per 10 gals. of gas and a quart to the crankcase. Your measurements or theirs for 247k miles??

OK jc... Double checking.... MMO bottle says 4 oz per 10 gals. of gas and a quart to the crankcase. Your measurements or theirs for 247k miles??


only use MY recommended amounts ! that is why I stated this correct amount...do not use what the bottle says..that is too much ...more is not better...my amounts only..

Excellent.... That's why I double checked... :) Will keep you posted...

i used both products in the oil and both seemed to work equally well as far as i noticed. and i had no adverse effects with either. i would also run some sea foam through the fuel system. the first time i did this i was shocked. with in a small amount of driving i noticed and increase in power and beter responce. i was impressed.

I'll never understand why people will purchase the cheapest mineral oil they can lay their hands on, then eagerly spend another $10 on some "magical" oil treatment that is advertised to cure all the problems caused by the inferior oil. Why not just use better lubrication in the FIRST PLACE? Mobil 1 or Amsoil will clean away sludge and varnish without super secret special magical marvelous additives.

Those who are so willing to believe the myths about ultimate awesome magical super hero additives are not surprisingly those who probably also believe the myths about PAO engine lubricants.

You're getting cold start lubrication problems? You're getting sludge (undoubtedly from degraded polymers added to crap oil)? You're getting varnish? Do a little empirical research. See why fleets, military, purpose-critical users (like backup generators in hospitals), those people who buy expensive, high-end engines, and millions of informed users don't use mineral oils.

I've changed to synthetic in engines with over 160K on the clock and not had problems, both liquid and air cooled. What's the excuse now? Unless the engine is already burning oil due to wear form previously inferior lubrication, there isn't a reason, only excuses. It doesn't even have to cost more. You can run a good synthetic for 10,000 miles with only an interim filter change and top off. That's less cost than cheap mineral oil changes every 3,000 miles (which should be the maximum for multi-viscosity mineral oils).

2¢

synthetic oils are the best to use in our engines..its been many years now of using these oils and the filters and engine have no sludge or any oil /gasket leaks..

the use of the marvel mystrey oil is however a great product when properly used in the fuel and crankcase to clean the build up of carbon and other contamination...

I have said this many times the MMO is used in all my engines and I have yet any to fail..from the chain saw to the truck it is a great lubricating product....the engines in my vehicles, even with the cold weather we have now , start with ease and no lifter noises...

even with synthetic you will get carbon deposits...especially when your operating in cold temps with damp weather...

Yes, additives can help to rapidly clean up accumulated sludge and varnish, and may be warranted in an extremely dirty/neglected engine. Once the initial cleaning is done, synthetic will continue to clean and keep clean the interior.

You are correct that carbon can accumulate in any engine, but once the engine and oil are at normal operating temperature (about 15 minutes of running) the outdoor air temperature is all but irrelevant and the synthetic will clean up any of the cold start carbon better provided there is a good filter installed to catch it.