Oil type & OCI advice for Air-Cooled car engine

[hid3]

Hello,

I've got a car from Soviet era which has the following engine:
1200cc, 40 HP, 4-cylinder, 4-stroke, V-shaped, gasoline powered carburettor injected, pushrod flat-tappet valvetrain with bottom-mounted cam, 7.2:1 compression ratio and no full-flow oil filter.

Oil filtration is achieved by by centrifuge which is bolted on to the crankshaft and spins at the same speed the crank does.

Engine design dates back to 1960s. Owner's manual recommends oils defined by standards which do not exist for decades; specified motor oils are not possible to convert to "modern" viscosity grades nor specs.

The big question: what oil should I use in this engine? And how often (miles/hours) should I drain it?

Folks in local club recommend mineral oil due to abscense of oil filtration system and suggest chaning it every 1000-1500 km.

Oh, and the car is being used only occasionally and accumulates around 1200 km per year (driven only in summer period). Oil temperatures I'm seeing usually are 90°C-100°C (200-210 F).

Thanks

 

[Eddie]

Sounds like a 30 or 5w30.

 

[barbersurgeon]

10w40 mineral would be my guess

 

[JohnnyJohnson]

Name brand of car?

 

[hid3]

Name brand of car?

ZAZ 968

 

[JavierH19]

15w-40 would be my choice for an easy to get oil. Not worth bothering with 10w-30/40 or sae 30.

 

[We're Metals]

Changing it often is going to be the move here. Otherwise, a 40w should be fine. Its not a shared gearbox with engine oil right?

 

[wings&wheels]

Assuming no cold weather use Valvoline VE1 20w-50 or, if the engine is clean, I would consider M1 V-Twin 20w-50. A 15w-40 with adequate additive levels would also be good as would M1 15w-50. The absence of a filtration system has no bearing on syn vs mineral as both will suspend contaminants. Assuming you don't use leaded fuel, but if you do syns are probably a no-no.

Are you also considering a lead substitute if necessary?

Cool vehicle.

 

[cb4017]

Back in the day I used Castrol GTX 20w-50 in my old air cooled VWs.

 

[hid3]

Sounds like a 30 or 5w30.

10w40 mineral would be my guess

15w-40 would be my choice for an easy to get oil. Not worth bothering with 10w-30/40 or sae 30.

Back in the day I used Castrol GTX 20w-50 in my old air cooled VWs.

5w30, 10w40, 15w40, 20w-50.... But what about Specifications? Should I stick with something rated API SL (or older spec) due to flat tappet, pushrod design or are newer API specs also fine?

Changing it often is going to be the move here. Otherwise, a 40w should be fine. Its not a shared gearbox with engine oil right?

How often is 'often'? I'm thinking about changing it every season or every 2nd season, in the spring, to get all the moisture out. That'd mean every 1200 km or every 2400 km accordingly...
And no, not shared with gearbox/clutch. Gearbox has its own oil pool but that's another question. Each gear makes it's own unique noise, you can distinguish which gear the car is in even being blindfolded (not seeing/feeling the car's speed )

Assuming no cold weather use Valvoline VE1 20w-50 or, if the engine is clean, I would consider M1 V-Twin 20w-50. A 15w-40 with adequate additive levels would also be good as would M1 15w-50. The absence of a filtration system has no bearing on syn vs mineral as both will suspend contaminants. Assuming you don't use leaded fuel, but if you do syns are probably a no-no.

Are you also considering a lead substitute if necessary?

Cool vehicle.

Absolutely no cold starts / warm weather only. Car hits the roads only when temps are 10°C / 50 F or higher.
Isn't M1 V-Twin 20w-50 a morotcycle oil? What's the difference between motorcycle and passenger car engine oil?
Regarding no difference of synthetic VS mineral - members of our local club have different view on this - they specifically recommend mineral because it's not able to hold contaminants in suspension - contaminants are getting centrifuged or settle out in the pockets or an engine thus reducing risk of getting some dirt into main or rod bearings and doing damage.
The engine itself is dirty - there's lots of black residue everywhere. Basically it's cooked oil / sludge / blow-by gasses.

Lead substitute: no, I don't use it. It's not required as there are cast-iron valve seats.

And yeah, the vehicle is a cool one. I like it. In each and every aspect it's different than most (if not all) of them on the road

Thanks!

 

[cb4017]

In your case I would probably use a 15W-40 HDEO that is also rated for gasoline engines.

I'm using this Super Tech in my old 4.0L Jeep. Runs fine.

ST Oil

 

[hid3]

I might be wrong but I think at leaswt 90% oils in the market in EU are rated for both, gasoline and diesel. So whichever I'd choose would be 'HDEO' (I assume so...)

 

[facility1]

probably a euro 10w30 maybe your best to try first, then see how it stays in engine, if not go up to a 10w-40 ,a high milage version.

 

[akela]

Engine design dates back to 1960s. Owner's manual recommends oils defined by standards which do not exist for decades; specified motor oils are not possible to convert to "modern" viscosity grades nor specs.

Back in 1960s-1980s, soviet oils were marked by their kinematic viscosity at 100C.
Correct me if I'm wrong, but my guess is - owner's manual recommends oils with viscosities
8 cSt in for the winter ("M8")
12 cSt in the summer ("M12")

Probably straight weight, because that's what was available when the engine was introduced.

So, 15w40 fits.

 

[hid3]

Back in 1960s-1980s, soviet oils were marked by their kinematic viscosity at 100C.
Correct me if I'm wrong, but my guess is - owner's manual recommends oils with viscosities
8 cSt in for the winter ("M8")
12 cSt in the summer ("M12")

Probably straight weight, because that's what was available when the engine was introduced.

So, 15w40 fits.

You're absolutely right, M8 and M12 for winter & summer accordingly. But are you sure it's cSt number? Soviets are known to invent their own things/systems so I have little doubt it's cSt...

Also, any ideas if these oils were just simple "oil" or it also contained additives?


Regarding oil recommendations posted in this thread - OK, I've got multiple viscosities offered but what about API (or other) ratings? Which specs should I choose?

Thanks!

 

[ka9mnx]

It's an old and Soviet vehicle. I would be looking at an ACEA oil and forget API. Look for oils with ACEA A3/B4 .

 

[vwmaniaman]

If it is a sedan, straight 30W detergent oil. Car was probably designed for that.. Fancy synthetics were not on the menu at the time it was built.

 

[vwmaniaman]

On my old VW Beetle I change my oil at 2K miles.

 

[akela]

You're absolutely right, M8 and M12 for winter & summer accordingly. But are you sure it's cSt number? Soviets are known to invent their own things/systems so I have little doubt it's cSt...

Also, any ideas if these oils were just simple "oil" or it also contained additives?


Regarding oil recommendations posted in this thread - OK, I've got multiple viscosities offered but what about API (or other) ratings? Which specs should I choose?

Thanks!

Yes, according to wiki article (in Russian), the number is indeed cSt at 100C.

Regarding additives, my understanding is, M8 (or M10 or M12) contains some amount of detergents (while previous generation of this oil, AC-8, was without additives). I don't think there were any anti-wear additives or friction modifiers (although this doesn't mean the engine wouldn't benefit from them).

API ratings are pretty much irrelevant to this engine. In my opinion, the important factors are (1) viscosity and (2) compatibility with the centrifugal filter.

 

[hid3]

API ratings are pretty much irrelevant to this engine. In my opinion, the important factors are (1) viscosity and (2) compatibility with the centrifugal filter.

Thanks. Any hints on how to check oil's compatability "with centrifugal filter"? I don't have any clue on that