So i have an 07 is350. It has 200000km on it and I notice what sounds to me like the lifters are a little loud so I’m guessing gummed up a bit. I was wondering if its safe to add an additive to the oil to help with this. I have always been wary of adding oil or fuel additives to any car as I’ve heard horror stories about it but i mean I’ve also head good stories. What’s everyone’s take? Thanks for your input

 

The oiling system on our engines is quite decent, and I'm unaware of any risks to the bearing surfaces or any seals from oil additives. I regularly will run a quart of Marvel Mystery Oil in between oil changes to help with carbon buildup, as the MMO burns off, it softens caked up carbon...much more dramatic results on a 5.9l Cummins, though.

All that said, I'm betting you're hearing either the coils or the injectors. Denso likes you to hear their equipment, apparently.

 

Im almost sure it’s not injectors as it’s gotten louder over the past 20000km but I’m not positive. It’s going in for service next week so I’ll find out more then. Just thought I should ask before

 

Grab a long wood dowel or screw driver and place one end in your ear and the other to the head, valve covers, injector tops and see if you can isolate the noise.
The HPFP is driven by the cam and actuates at 1/2 crank speed, so give that a good listen too. It thumps pretty solid.


In my experience I hear these engines get a bit louder towards the 4500 mile mark on the OCI, then take a couple hundred miles to get quiet again after OCI. Some will laugh but that syrup cr@p called STP serves one good purpose - during start up, it sticks around. No imperical data here except 2 engines from our sand rail tossed in storage and 3 years later I grabbed them pulled them apart. The one with STP still had lubrication at all critical points - rods, mains, pistons, rings, lifters, valves....
The other was bone dry. Granted thats oil technology from 20 years ago but it was obvious when turning the crank on those during disassembly too.

I use it today whether it needs it not!

 

I picked up some MMO I’ll start adding to my fuel and when I do the oil on Thursday I’ll add it there too. See how that goes

 

Look up Zinc, ZDDP, Zinc dialkyl dithiophosphate and see what roll they play in engine health. Now look and see if your product has any of that in there. If no, switch products to those that do.