The story of my first DIY oil change on my recent 1976 300D purchase:

First, I went to my local NAPA to order the filter. I told them what I had, and the guy went through his books in short order- said "inline 5?" I said "yup". So, after 2 days the filter arrives and I picked it up, then proceeded to local truck stop to get 8 quarts of REAL 10W30 diesel oil.

Now, I get home, jack up the front of the car, and crawl under with my 17mm socket and remove the filter. Oil everywhere, but that's an old story. Immediately I noticed that the filter I got from NAPA was twice as long as the one in my car, "it figures" I say. (I should be posting on the Vintage Forum, I know, I know!) Anyway, NAPA is now closed for the evening, so I simply proceed to drain the crankcase and plan to hit NAPA first thing this morning. They went back to their books and kind of scratch their heads- on a hunch I told them to check listing for 240D instead of 300D. Now it says that for a '76, they're the same, but if they go back to '75, they are different. NOW, I got lucky- the '75 240D filter they had right in the store! Why? Because it's the same filter as for a freakin' Massey Fergusen tractor! I had my old filter with me, dripping black blood into a plastic bag- we held them side by side and compared dameters- pretty close we all agreed, so he refunds me the difference and I head home.

When I opened the box, there are special instructions inside "for use with Mercedes Benz autos". Excellent! Basically all it said was to use the plastic disk, which I had, and not to use the supplied O-Ring- use the MB one instead. Great!

So, underneath I go, with the assembly, including the disk, but for the life of me I couldn't get the housing bolt to engage into the engine block. I'm not a burley mechanic, so someone with more strength might have done it, but I couldn't. So, after almost breaking my arm I took a closer look. I noted that compared to the old filter, the Massey F one seemed to rise out of the housing by about 1/8" more, and also it had a metal rise in the centre about another 1/8" which adds 1/4" to the total height. So I decided to install the thing without the disk, even though the special instructions said to use it. Ha- it bolted right up- a few quick turns of the ratchet and I was in business.

Now, I poured in my oil, fired up the engine, and watched the oil pressure build to max, which seems to be normal on my car until fully warmed up, then it will drop to half at slow idle. I quickly peered underneath looking for leaks. Kept peering- no leaks. Went back to look at pressure guage- still at max. Let engine warm up- pressure dropped to half. Everything seems normal.

So far no disaster, but I have a question for the experts- is there anything about using this tractor filter without the disk that would make you say "don't drive that car! Get the right parts and have it towed to a garage"? Naturally I'm going to keep a close eye for leaks, dropping pressure and oil loss on the dipstick, and my next oil change, before I put "Pearl" away for the winter will be done at MB dealer with the exact right filter, and the disk. But am I in serious jeopardy until then? Is anyone else aware, or experienced with the tractor oil filter?

Dave Milton

White '76 W115 300D- "Pearl"
'98 Chevy Cavalier- wife-mobile and "just in case"