A friend's XJ has valve tapping when warmed up.
Any easy way to address this?

 

Are you sure it's valve tap?

If it is, it'll need a head rebuilt. Valves, springs, seats, etc.

 

What about some Seafoam or Marvel?

 

If it's truly valve tap that won't do anything. You could try marvel just for the sake of its a great product and it's good on the engine. I run a quart every other oil change, and run it in my gas

 

I don't agree. Modern oils don't need additional additives. You are only diluting their additive pack, which could prove harmful.

Your engine is not a 2-stroke or a diesel. You don't put oil in the gas.

What you are doing is an unnecessary waste of money and resources.

If it was a "great product" and "good for the engine", new car manufactures would use it. None do.

 

Read some reviews, many people use it and I have had nothing but good from it. My dads s10 had a few gunked up injectors, after a few uses of marvel they're clean.

 

If it's a sticky lifter, as I suspect, MMO may help.

 

Or this.

 

there's a sucker born every minute. if the jeep is making substantial metal on metal noises there is no fix. take it apart and repair it correctly, otherwise you're just wasting time and money on something that will not repair anything. engine additives are comical and I wouldn't even use mmo to start a fire. junk.

 

I wouldn't exactly consider lifter noise substantial.. If it's lifter noise marvel is definitely the way to go, it's a great product that shows it and has great results. Don't be ignorant about additives. A lot of them are yes, snake oil but that doesn't mean they all are.

 

He's from Indiana.

 

If you are a paid spokesman for Marvel Mystery Oil, disclose it now.

If you are not, you sound like one. They might be hiring.

 

I've used marvel repeatedly on different things. speaking from personal experience - I find it useless.

and lifters are not valves, btw.