Just passing on my experience with an additive. I use Techcron, seems to do the job and has been recommended extensively. I also keep my 240 wagon well tuned and serviced regularly; however, many months ago, I had begun to develop an irregular idle and some occasional "clicking " sounds emanating from the injectors. Using Techron didn’t help. I went to my mechanic and was dreading perhaps a valve job, injector replacemnent, etc. He listened to the sounds, and instead of diving into a large possible "repair", suggested I first try Marvel Mystery Oil. I informed him I used Techron regularly. Now I have heard of and seen Marvel Mystery Oil (MMO) on the shelves of various places such as Kragens, for many years, never giving it much credence. Well, on my mechanics’ recommendation, I purchased a small bottle of it and following directions, put it in my gas tank. You can guess where this is leading. Yes, it worked!! The engine smoothed out within less than 2 tanks, and has never run better since I have owned my 240, for the last almost 5 years. Apparently my injectors were “sticking” and Techron just wouldn’t “unstick” them. I now use MMO about every 2-4 tanks, about 6 ounces at a time, and after quite a few months, the old engine is still doing very well!! I'm sold. Now, I do not use MMO in my oil although the directions say you can. I just don't feel any need to try it for that. Apparently, MMO works differently than Techron, adding vital lubrication qualities to the fuel, and no, there is NO smoke from it that I see coming from the exhaust, as I wondered there might be since it apparently is an "oil". I now buy it in the largest size I can, (for economics) and I fill my small bottle with it using a funnel. The reason for that is the small bottle is easier to use and it has measurements on the side so you can see how many ounces you are pouring in.

Here’s my disclaimer: LOL! No I do NOT have any “business interest” in MMO. I just like to pass on something that has worked well for me. I hope it might work well for someone else. Drive safely.

While I don't believe in additives, Marvel Mystery Oil is one of the best things for cutting loose the carbon build up in the engine. The method I've used is to remove the spark plugs, fill the bores, and let it soak for a day or two. The added benefit is the reduction of mosquitoes in the general area of the restart.

I've also used it for storage prepping a marine application, especially those used in saltwater.

Regards,
--
Will Dallas, www.willdallas.us, www.willdallas.org, www.willdallas.com 86 245 DL 222K miles, 93 940 260K miles, 88 765 GLE 152K miles, 87 Honda Civic 96K.

I used to use MMO in my car. One day, however, I was reading my latest bi-monthly auto newsletter, Nutz & Boltz, and I discovered the following response to a query about the benefits of MMO: "The old saw about adding MMO was true back in the days of non-detergent oils. Modern engine oils already have detergents in them, and the MMO will only dilute the lubricating ability of your oil. And the additives it contains will contaminate the oxygen sensors as well as the catalytic converter. can you spell "expensive?"

So use your own judgment, but I figured if there was a chance that MMO would contaminate my sensor or cat the benefits of MMO would be outweighed by the risks. Hope you find this useful.

Thanks for all your responses. Definetly deserves some thought. New cat or 02 sensor, possible valve job and/or injector replacement? How often might MMO cause any of that to happen, might be dependent on just how much MMO one might use? Well, on the plus side, I'm using a fairly minimal amount of MMO, 6 ounces every 2 to 4 tanks isn't all that much I would think? I might consider going to using it every 8 to 10 tanks depending how the engine functions. I do use it now as a "preventative" to the injectors "sticking" again. My mechanic has been in the Volvo repair business over 20 years, and he has used it in some of his own without issues for years. Could be using MMO minimaly would be the best thing if you're going to use it at all.

BTW, My 240 is an '89, 179K miles, excellent condition in and out. I do keep it serviced VERY regularly, oil, filter, tune ups, etc. Why the injectors "stuck" in the first place, I just don't know? Murphys' law I suppose. I imagine if my 240 needed 6 ounces every day or so of MMO to run, then I might be (much) more concerned, but I will keep my eyes open. My mileage is good, no smoke, idle excellent, passed smog with ease recently. Long term effects? We'll see and if I should develop issues due to using MMO I will let the Brickboard know. The messages I get are from "don't use any additives", to "be careful". As a last thought, this has been my personal experience. If anyone is considering using any additive, give some thought to what the BBer's say and your mechanic. Research it yourself. Drive safe!

You didn't mention what year your brick is. Don't get me wrong, I love MMO and what it can do, but I would be concerned about plugging up the CAT converter or O2 sensor on newer bricks.

On our 65 T-bird (390 V8), I run 1 quart of MMO in the crank case (rest is 10W40) and it quiets the Hydraulic lifters quite nicely. I also run a small amount of MMO in the gas. When I pulled the head off the last time (broken exhaust manifold stud), the valves were pretty clean with no major buildup but they were black in color instead of the normal tan color I like to see. If anything, the car runs a little lean and the engine only has 5K miles on it (since 100% rebuild).

In short, the engine will love it, but the cat and O2 sensor (if your car has them) might plug up on you.

jorrell

There has been a lot of positive postings over at bobistheoilguy.com on the use of MMO.

I never believed in "miracle" additives since I was a kid reading Whitney's Cat. Those engine rebuilding pills that went into the gas tank and worked miracles all seemed like a long shot. I HAVE had excellent results with MMO in the tiny flathead Atomic 4 in my sailboat. I hesatated at first when MMO was recomended by the Atom 4 Guru- but it really works to keep the side valves clean and prevents them from sticking. After removing the head to replace head gasket I DID find a heavy carbon build up. It could have been from too much MMO in the gas or from running too rich on a fixed main jet. I have an adjustable main jet now so in 5 years when I take the head off again I'll know for sure if it was MMO! I think the popularity of MMO for over 50 years must indicate it's good qualities. It was designed for flathead (side valve) engines many years ago and is a trade secret formula. I think I'll put a little in the 240 and see if it does anything. I only get 22 mpg and I use cheap gas. I wonder if mid grade will help? It is not a good idea to use ANY ADDITIVE in modern oil! Syn or Dino both have a sensitive mix of additives from the refinery and shade tree alchemy is only going to upset that balance. I really like MMO in the boat and use it every time I fill up- usually twice a season!!!!

My favorite additive is Liquid Timing Chain...