1978 BMW E21 323i - too much to choose from..

[Lockguard]

Hi,

I recently became the happy owner of a BMW E21 323i from 1978 with the M20B23 engine. This is my first experience with classic motoring.
It just had an oil change before i picked it up - don't know what type was used though. Wanting to take proper care of it, i started to search for oil, just in case it would need topping up, and boy did i get myself confused.

I live in Denmark where temperatures range between -15°C (+5°F) on the coldest winter day and a little over 30°C (86°F) on the hot summer days.
Now i know it's all sorts of wrong and forbidden to take a classic out in the winter, especially if the roads are salted - but i can't rule out that it's going to happen from time to time. I bought the car to use it after all.

BMW recommends a 20W-50 oil for year round use above -10°C (+14°F), but i think that is too close to the limit of what the car might experience and i fear that a 20W might be a bit hard on the cold engine. They then recommend 15W-50 oil for year round use above -20°C (-4°F), however i can't find much to choose from in this viscosity. Bear in mind, these are over 40 years old recommendations and i suspect quite a lot has happened to oil since then.

Asking around a few people suggested Castol Edge 10W-60, which i thought sounded nice, since a 10W would be better for cold starting, and it's generally a high performance oil.
Then someone else strongly advised against it, since it's low on ZDDP-content. Don't know the values though.
Asking more people just resulted in more different answers and options, and no real progress for me. One persons holy grail seemed to be the devils creation to the next.

Having stubled upon this forum a few times in my search, i decided that maybe i should ask you guys - so here i am!

I have found the following options:
Mobil oils seem to make a few people happy as well, and the Mobil 1 FS X1 5W-50 looks fairly promising in my eyes - but i'm no expert. As far as i can see, the X2 variant of this oil (no clue what the difference is) has a ZDDP content of 1100 ppm. Trouble is i don't know if that's plenty fine for my car, or if it should be higher?

I also found a 10W-60 synthetic with 1800ppm - but it's made by a local brand i have never heard of before, so i don't know how comfortable i would feel using this oil. It might be based on the classic Castrol oils though, but i don't know for sure. Otherwise this "Revival Classic V67 YTH 10W-60" sounds pretty decent.

I could also use the Castrol Classic or Gulf Classic 20W-50 in the summer months and then change to another oil for the winter, but i have no idea what to go for then.
BMW does recommend the oil to be changed every 6 months or 7500 km (4600 miles), but again that's based on 70's oils. Not that i would go over on the mileage though.

What would you suggest that i do? Are there any other oils more suited?
Bear in mind that some of your suggestions might not be available for me here - i've never seen Shell Rotella for example, but i don't know if they just call it Helix over here or if that's completely different.

Thanks!
-Alex

 

[Pelican]

When that BMW was made the oil selection was very very limited. I think you can go happily with Mobil1 5W50

 

[MCompact]

Originally Posted by Pelican
When that BMW was made the oil selection was very very limited. I think you can go happily with Mobil1 5W50


I ran M1 15W-50 in my older BMWs and I was very happy with it.

 

[toneydoc]

Mobil 1 15w50 will meet your needs

 

[talest]

A lot of people end up using Castrol 5W-50 in this vintage BMW. These vintage cars always seemed to like thicker motor oil, it is true,

unofficialbmw.com is also still a good resource. I had one, slightly newer than yours. It is a GREAT car.

 

[Lockguard]

Thanks for your inputs!
Do you mean the Mobil 1 Racing 4T, 15W-50?
It's the only one I can find and it looks like it's aimed at motorcycles, which i suppose isn't necessarily a bad thing, given how such engines are run.

 

[dave1251]

Go with the Mobil One it's looks like the best all around PCMO for use in Denmark.

 

[Lockguard]

Originally Posted by talest
A lot of people end up using Castrol 5W-50 in this vintage BMW. These vintage cars always seemed to like thicker motor oil, it is true,

unofficialbmw.com is also still a good resource. I had one, slightly newer than yours. It is a GREAT car.

Is that Castrol Edge supercar stuff? Won't that be like the 10W-60 regarding ZDDP? Or is that not really an issue on these engines?

Thanks, I'll check it out!
Yeah, it's a wonderful machine!

 

[ka9mnx]

The owners manual for my 1987 325 never mentioned viscosity. They only recommended an oil with an HTHS greater than 3.5. That was before ACEA but I would imagine they would want an ACEA A3 B3/B4. I used, at the time, Mobil1 5w-40 which was as close as I could get with an HTHS of 3.4. I would look for an oil with those specs regardless of grade.

I was spent time in Denmark with the US Air Force. Loved the place. Very friendly people that liked Americans. I could live there...

 

[talest]

Originally Posted by Lockguard
Originally Posted by talest
A lot of people end up using Castrol 5W-50 in this vintage BMW. These vintage cars always seemed to like thicker motor oil, it is true,

unofficialbmw.com is also still a good resource. I had one, slightly newer than yours. It is a GREAT car.

Is that Castrol Edge supercar stuff? Won't that be like the 10W-60 regarding ZDDP? Or is that not really an issue on these engines?

Thanks, I'll check it out!
Yeah, it's a wonderful machine!


I just want to point out quickly that you are in Denmark, and oil selection may be different than we in the

That said.. This is the Castrol 5W-50. It is sold by the quart at major auto parts stores in the US. It's not the same as the 10W-60, you are correct it can have whatever ZDDP it wants to in there due to it being a 50 but if I recall, this was an API SL oil. It may be newer now. https://www.castrol.com/en_us/unite...Do_g_3DANTbJym4_KQJY1IOB5IwaAsXzEALw_wcB

The Castrol was always pretty readily available and a lot of people like Castrol, it is not uncommon to find Castrol 5W-50 in an older BMW engine.. M20B25, M20B27, etc. http://www.unofficialbmw.com

The other suggested oil as Mobil 1 15W-50 or 5W-50, I should be the one to point out that M1 15W-50 performs more like a 10W-50 it is just the labeling. I forget exactly where I heard this, but even the reviews on Amazon indicate it has great performance.

The Mobil 1 5W-50 is the super unicorn of the bunch, being a very specific oil that I always had thought was hard to get, maybe you can order it from somewhere online but. If desiring to use these and if not wanting to use a 10W-40 or something thinner than a 50 (I used to use 5W-50 in the wintertime and may have used 5W-40 a time or two, depends on how cold it gets by you, some people even use different oils) that one also should do well.

This BMW is a very old school engine and seems to like a nice thick oil to stay thick during all that heat, also seems to like to have quarts disappear if you go too thin, like, say, a 30-weight. Surely there have been some that have tried 30 in there and ended up using maybe a 40 or 50, due to the oil light coming on while driving indicating low oil level not pressure.

 

[RooflessVW]

In Denmark? Mobil 1 10W-50 should be available in your country and I would use that.

 

[ChristianReske]

Since you live in Denmark, Ravenol should be available?

- RAVENOL HVE High Viscosity Ester Oil SAE 10W-50
- RAVENOL HVT High Viscosity Turbo Oil SAE 5W-50
There is a dedicated Racing oil:
- RAVENOL RSE SAE 10W-50

Saying this, i confess that i am NOT a big fan of Ravenol. Additional, you could do a search by yourself at the Homepages of such Manufacturers like KROON OIL, EUROL, ADDINOL.

More to choose are:
- Fuchs Titan SuperSyn 5W-50
- AMSOIL Signature Series 5W-50


If this would be my car, i would choose between the Mobil, Fuchs, Amsoil, Castrol.

 

[edyvw]

15W40 or 15W50 would be fine in Denmark climate.

 

[Lockguard]

Thank you all for your great inputs! Much appreciated!
Just to clarify - the 15W-50 oils you suggest, they are actually marketed as motorcycle oils right?

If so, my options are the following (excuse the danish in the links)
Mobil 1 Racing 4T 15W-50 - https://www.oliebiksen.dk/shop/mobil-1-racing-1026p.html
Castrol POWER1 4T 15W-50 - https://www.oliebiksen.dk/shop/castrol-power1-4t-1658p.html
Castrol GTX 15W-50 - Car oil - https://www.oliebiksen.dk/shop/castrol-gtx-15w-50-1935p.html

Alternatively, the Mobil 1 5W-50
MOBIL 1 FS X1 5W-50 - https://www.oliebiksen.dk/shop/mobil-1-fs-1012p.html

 

[FCD]

Mobil 1 15W-50 does not exist in Europe, only in a version called Racing 4T which is for motorcycles and hyper expensive.

 

[FCD]

To the OP, Can you find Valvoline VR1 20W-50 in Denmark?
It's a very good oil for classic cars with flat tappet camshafts, it also however meets modern specs, API SM and ACEA A3/B4.

Mobil 1 5W-50 would not be a bad option if you also use the car in the winter, however it will probably make your engine noisier than with other oils, and expect to see more oil leaks, oil consumption and probably lower oil pressure than with say a 20W-50 Mineral oil.

Another possibly good option would be a 15W-40 HDEO like Shell Rimula R4X ( to our American colleagues think of this oil as Europe's Rotella T4 ), it's an old school "full strength" 15W-40 Mineral HDEO which has around 1200ppm of Zddp, and is available in most of Europe.
Mobil Delvac MX 15W-40 also should have if i remember correctly around 1100ppm of ZDDP.

 

[Lockguard]

No luck on the Valvoline, and the only Shell oils we can get here is the Helix-series.
I didn't think about that the 5W-50 Mobil 1 might cause increased noise and leaking (it's not leaking anything at the moment). It would probably have to get fairly cold before it really benefits from the low W-viscosity.

I think i would prefer a 15W-50, but they are few and far between. The only one i seem to be able to find aside from the motorcycle stuff is the Castrol GTX
https://www.oliebiksen.dk/shop/cast...VOYfw37Gi1f6FKEPQRitiGbhuZhoCRG0QAvD_BwE
but i don't know how this performs compared to others.

Looking at weight-to-temperature graphs again, i might have been a bit hard on the 20W-oils. Some days it could be close to the recommended temperature limit (-15°C/+5°F), but it would not be many days. Most winter nights here are not colder than -10°C/+14°F.

Would it be too hard on the engine to run a 20W-50 year round?

All in all, i think the following are my realistic options:
5W-50 Mobil 1
15W-50 Castrol GTX
20W-50 Castrol Classic
20W-50 Gulf Classic

Going to a 15W-40 opens up for Mobil 1 Super 1000 X1, but i think the car prefers xW-50?

Sorry if it seems like i'm asking the same questions again and again, but i get lost in this giant world of similar products that are not similar at all..