Introducing my 1980 300SD, “Patience” and a few oil change questions

[avantbenz]

Hey all, this is my introduction to the forum. I just picked up my 1980 Mercedes 300SD. She has about 167932 miles - her odometer literally just stopped.

It took a very long time for me to take possession of the car as the person I bought it from had some things he had to get done before passing it on. One week turned into seven months. It was extremely frustrating.

My first order of business is to change her oil. I've changed oil in other cars before (Honda, Audi, Fiat) but since she is new to me I'm looking for help! It seems like she needs a min of 6.6L of oil (max 8.6L) which is a ton of oil. I'm looking at Shell Rotella or Mobil Delo based on recommendations from Mercedes-Source. I'm still looking for an appropriate filter - my local AutoZone recommended a STP S2930 but it looks like it's engineered for synthetic oils (which I won't be using).

The most important thing I need is the proper tool for the drain plug. I saw someone say something about a "special hazet tool" needed to remove the drain plug. What is this? Where can I get it?

I'll have a bunch of other stuff I need to take care of soon. One of the front headlights appears to be out but I don't think it's a bulb because it'll come on when I flash my high beams. I also need to replace the female end seat belt clip on the passenger side.

I look forward to joining the community! 

[ptashek]

Welcome to the asylum

As for oil, one of the diesel owners here -Squiggle Dog - was always praising Amsoil oils. Try searching the forum for it, there's bound to be more details.

According to my workshop reference, you will need 7.5 litres of the stuff, with filter change (8.5 litres is dry fill at factory).

[Harv]

Welcome to the club.

I like this stuff in both my OM616 and OM617. Nice and cheap. Change it every 3,000-3,500.



Grab a filter from here: https://www.pelicanparts.com/catalog/SuperCat/3334/MBZ_3334_BASFLT_pg2.htm#item5

Any brand works. They have a warehouse in Cali so you should have it in a day or two.

[rumb]

Dont forget the "Library" here has manuals in it.

https://www.w116.org/library/

[Squiggle Dog]

Nice looking car! And with less than half the miles of my own, you can rest assured you'll get many more miles out of yours. Your car's previous owner reminds me of my car's previous owner--he made a big deal about needing me to meet him right on time at the train station and then he conveniently didn't have the title after I had already ridden the train from out of state. The car barely made it home and then I had to nag him for months to get the title. I suspect he had given the car to his girlfriend and then he had just broken up with her and was trying to get the title from her. He was a shady character, to say the least.

All you need to change the oil is a 13mm socket for the drain plug (I think that's the correct size, anyway). Some really old Mercedes engines use a large hex key socket. Then you need to remove the oil filter on top of the engine by the brake booster with a 10mm socket (there are two nuts holding on the lid). From there you can carefully pull the filter out while trying to not drip oil all over. Then you slide in the new filter and install a new large O-ring in the lid.

I like using Amsoil 15W40 Heavy Duty Marine & Diesel Oil. It's synthetic and has proper levels for phosphorus and zinc for old engines. Because it's a heavy weight, leakage shouldn't be a problem since it's not a light weight 0W or 5W as are so many synthetic oils. I don't see a need to change it any more often than 10,000 miles. This oil is expensive, though, so you have to be able to justify it. Mine is my only drivable car, and has been for nearly 10 years. The engine will last longer and perform better, but if your car is only going to be for occasional use, it might not make sense to spend the money if you're not going to be putting on the miles.

I'm not sure about your headlight situation. If it's not the bulb, it could possibly be a bad ground or even a bad turn signal combination switch.

[orientrot]

For the headlights, you may just have had the low beam filament burn out or you may have a wiring or switch issue.

Regardless of what the issue is, you should check all of the body grounds on the car as part of initial maintenance. I would recommend replacing all the ground straps with new lower gauge braided ones. I did this and it got rid of the battery discharging problems I had. My car recently sat for nearly a year without starting because of a radiator leak and without the battery being on a maintainer and I was pleasantly surprised to find that the car started without drama when I finally fired it up again. After making the change, I noticed that the stock headlights were much brighter and the horn changed pitch because it was finally getting correct voltage. I would also highly recommend getting rid of the sealed beam headlights and invest in some H4 replacements (Cibies are generally the best regarded). It's cheaper than finding a good set of Euros and the round H4s actually give a better light pattern than the Euros do.

[Squiggle Dog]

If I remember correctly, the grounds for the headlights and glow plug system are near the left side (driver side for you) of the radiator and use a 7mm bolt and nut. I know this because on my previous 300SD, it had already been parted out and the previous owner had cut and removed the entire front wire harness (all this, no fuses or alternator, no belts, no exhaust, no air cleaner, no lights, no bumper, and the previous owner said it would make the trip nearly 100 miles home--good thing I brought a trailer).

It's interesting that the North American-model W116s didn't come with rectangular sealed beams--they would have fit better and would have given better light and possibly looked a lot better. I've seen several Euro headlights that have had rectangular sealed beams screwed into the reflectors after they tarnished too much.

[avantbenz]

First off, thank you everybody for your responses! I'm excited to have this car and even more excited because there is such a robust community of W116 enthusiasts! I know it'll help me get the most of out of her, and hopefully what I post can help someone else out on their journey. I've done a fair bit on the car already and have a looooong laundry list of other things I need to address. I think I'll start a project thread but first -

I rather like the round American style headlights so I think I'll end up upgrading to the H4's at some point. Thanks for the tip, orientrot!

The headlight issue turned out to be an old fuse which when replaced restored my low-beam lights. Now I just need to order a bulb for the hi-beam that's still out - I'll check out pelicanparts because I can ony find a hi/lo-beam replacement bulb at all the local parts store and since the hi-beams are hi-beam *only* lamps I want it to stay clean.

The female seatbelt end turned out to have a foreign object in it. It really, really looked like the inner clip was open when I inspected it with a flashlight but about 3 minutes of compressed air released whatever was preventing it from locking and we're all good!

I went with the Shell Rotella oil for the first change and I might switch it up in a few months when my next oil change is due. SquiggleDog, thanks for the synthetic recommendation (and the list of required tools) - I'll give it a go the next round.

Here's a link to the project post: https://forum.w116.org/test-drive/the-patience-project-my-1980-300sd/

Thanks again, everyone!