You need to replace your thermostat, which is stuck open.

The Auto-RX will work, and help silence the engine. My lifter tapping was not bad, but now is completely gone. On (very) cold starts there was also a less-noticeable clacking, I assume from the rockers, which went away as the car warmed up. Now it goes away in just a few seconds, and I assume it will be gone completely, just like the lifter noise.

Finally, the normal "roar" of acceleration, which on my car is most noticeable in the 2300 to 2700 rpm range, is now about half as audible as it used to be, and continues to get quieter. (On acceleration above about 2800 rpm, or below 2200 rpm, the engine is extremely quiet - - cannot be heard over wind and tire noise.)

As the oil passages, rings and seals continue to be gently cleaned, the good results should continue.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

I know. I need to make myself pay up the $30. for the thermostat. I know it must be stuck open, but whats strange is that when it idles (especially in the summer) for more than 10 minutes, the temp goes up to 110°C. I know that my auxillary fan is on the fritz, so perhaps the PO removed the thermostat because of that?

I have noticed that my engine is quieter. I have only put about 110 miles on it since I have added the RX. Hopefully the quietening will continue. Many more miles to go. No more than I have to drive this car, it may take 6 months before I hit 2000 miles.

Save your self some time and money and used diesel rated oil. I have used the Auto-RX product and it seemed to work quite well, but now every third oil change (depending on mileage) I use 15W40 Delco.

The diesel oil does a great job of cleaning.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Does anyone have any independent study results of the Auto RX?

I have disassembled engines - not many - but, the ones running synthetic oil are clean - with light weight synthetics, I can't see how anything can really make the engines run any better, or quieter. I can see and hear a difference between synthetic and non-syn, though.

Is this sort of like the Water Wetter angle? With WW you add it to a lower ratio (coolant:water) and like magic it makes your car run cooler - when, it is simply the lower ratio that causes the cooler running (water is more efficient transfer agent).

Perhaps the AutoRX is simply a thinner version of the normally highly detergent synthetic oil that cleans the gunk out of engines that have been running on non-syn oils? Every time I have bought a used car and switched to synthetics the engine starts easier, runs more quietly with less lifter noise, gets slightly better fuel mileage, and is far cleaner internally.

__________________
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg

The removal of dirt and contaminants will make them run better, which is evidently what Auto-RX does.

There is an interesting thread at Bob is the Oil Guy. Synthetic blends (but not pure synthetics), according to the argument, can contribute to engine sludging and leaky seals:

http://theoildrop.server101.com/forums/showflat.php?Cat=0&Board=UBB5&Number=272514&page=184&fpart=all

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black