Synthetic oil for Air-cooled?

[roburswest]

Hi everybody. I am new to this site, and new also to the complicated world of motor oil. I have read the articles posted and now know more about motor oil than I care to admit.

My vehicle is a 1974, East German Military 4x4 troop transport. It has an air-cooled inline four cylinder gas engine. The owners manual calls for 8L of 15w40. I would like to go to a synthetic oil and am looking for suggestions, mainly, is that a good idea or not.

Some air-cooled websites advise that synthetic oils can reduce oil temp, but actually increase cylinder head temps. They also say synthetic should not be used in aircooled engines which still have stock oiling systems.

Most of the 15w40 oil i have seen is labeled specifically for diesel trucks, and i am curious if there is a reason not to use it in heavy duty gas engines. Or would it be wise to switch to a lighter, mineral oil.....0w40.....0w30...? So many choices. Suggestions?

 

[oggb]

I'd go ahead and run the 15w-40. If it's of German origin they were probably planning on ambient temps below what you'll see in NorCal and the 15w-40 oils then weren't anywhere close to what they are now.

Use a good 15w-40 like Delvac 1300 Super and you'll be peachy.

 

[MrMeeks]

15w-40 is my choice.does this engine use an oil filter?

 

[Doug Hillary]

Hi,
roburswest - Welcome to BITOG. You would be best advised to stick with a 15W-40 mineral lubricant - and a dual rated (diesel/petrol - eg CJ-4/SL) HDEO is fine

Delvac 1300 15W-40 is a great choice as an earlier Poster has advised

 

[roburswest]

Yes, there is an oil filter. It does not over heat, but it is really cold blooded and has a long warm up period, especially in the winter (temp here drop to the 20's at night).

Is it ok to use a 15w40 diesel oil for a gas engine?

 

[roburswest]

Would switching to synthetic be a mistake or just expensive?

 

[rclint]

I agree with others use a 15-40 mineral/conventional oil, and HDEO (heavy duty engine oil) is the way to go here for sure as the specification on this type of oil has not changed so as to impact your engine.. (PCMO) Passenger car motor oils have changed a bunch over the years, and not for the best if being used in an engine like yours.. As you said you have read up on this, and I'm probably just wasting bandwidth... additives have changed in PCMO because of engine design, and other things as well, rollers where tappets used to be etc..

As to oil choice then your getting into advertising here... and HDEO seem to be even more live/die by than the synthetic craze of recent... The oils I have used, and have had outstanding service from is Rotella, Delo, and Mystic all in 15w-40, and I have also used HD30 in these oils in one flavor or another.. never had a problem, but I now choose either Delo, or Rotell just depending on mood because I can't find another reason.

 

[rclint]

Originally Posted By: roburswest
Would switching to synthetic be a mistake or just expensive?


Switching to synthetic would be expensive for sure, and I don't see any advantages you would gain by switching to a synthetic. From what is said, read, put on this forum synthetic advantages are longer drain intervals, cleaner engines, and when specified by the manufacture for a certain condition such as extreme heat, HP output, or at times design flaws in my opinion... So you have to ask yourself do any of these apply to you.

Synthetics don't give you a cleaner engine in this realm, especially using a HDEO, and if any nit pick was cleaner it would have zero effect on engine life in any way. I don't think your going to be dealing with any extreme hp/heat issues, and the HDEO's of today will already be overkill for your engine.

Folklore can get into all kinds of things, most synthetics and in HDEO's will be grp III's, unless you get into some real real expensive money with Mobil synthetic (Doug has a lot of background on this subject) in this case synthetics are to extend drain intervals which cuts down cost on maintaining a engine, however your also putting out some hefty cost doing UOA's etc, and even at that many will want a oil change at a one year interval.. Synthetics are not "better" oils for the engine, synthetics just allow you more operating room so to speak... as in folklore with an engine the age of yours some people have reported, sworn, and even put up their first born that the synthetic oil caused oil leaks... I don't believe this, BUT if one were to choose a true group IV/V it may be possible with a older engine that it would clean, not be compatible with gasket material etc.. I can't believe I just said that as I'm not a believer in this for the most part..

If you stick with a name brand HDEO 15w-40 I think your engine will thank you, and you will have a long fruitful life, as well as your engine.

 

[Ken2]

Quote:
Some air-cooled websites advise that synthetic oils can reduce oil temp, but actually increase cylinder head temps. They also say synthetic should not be used in aircooled engines which still have stock oiling systems.

Synthetic oils are widely used in air cooled motorcycle engines. Check the oil shelf in any motorcycle shop...just look at the Mobil 1 motorcycle oils in any Wal*Mart.

(V-Twin is a euphemism for Harley-Davidson without copyright concerns)
--quote--
Mobil 1 V-Twin 20W-50 fully synthetic motor oil is designed for air-cooled, large-displacement bikes. Because of their design, these engines can generate very high localized oil temperatures and high overall bulk-oil temperatures.

As you know, a typical air-cooled V-twin's rear cylinder gets a lot hotter than the front cylinder – it's a matter of airflow. When it's hot out and you're stuck in traffic, the oil temperature in your bike climbs rapidly. Above about 250°F, conventional motor oil is going to break down. Mobil 1 V-Twin 20W-50 fully synthetic motor oil is good to above 300°F.
--end quote--
http://www.mobiloil.com/USA-English/MotorOil/Oils/Motorcycle_Oil_FAQs.aspx#FAQs3

I'd like to see the actual measurements of the type of oil increasing head temperatures. I'll believe it when I see it. The Mobil 1 motorcycle oil would be more expensive than you need to spend, but this is just an example of synthetic oils that work very well in air cooled engines.

 

[unDummy]

8L isn't a budget breaker.

Military vehicles recommendations might also consider replacing engine as a maintenance item.

Air cooled engines, if pushed, can possibly run too hot. A mineral oil might cook. Get an oil temp gauge. If oil temps are acceptable, then ANY new HDEO 15w40 is good enough.

Any full synthetic HDEO 5w40 is an easy choice. Valvoline, Schaeffers, Rotella T6, Amsoil, Redline, Mobil1.... are some.

 

[chubbs1]

I agree with everyone here also, I don't want to seem like a robot bandwagoner but as it was mentioned before oils have come very far from those back in the 70's. A conventional 15W40 oil will be fine for your engine and be able to take the cold well, the only other alternative is a 10W40 which I don't see being necessary where you live. Castrol makes a conventional 10w40 but it is harder to find (though I have not looked for that oil) Amazon has cases of 6 for $33 but that is pretty steep. Just go to Walmart and pick out a 15w40 in whatever jug you think is the coolest looking. It is that easy.

 

[Doug Hillary]

Hi,
roburswest - One reason why I suggested you stay with a mineral lubricant has to do with the origin of the engine. I have had a bit to do with the old Eastern Bloc's vehicles and such things as gasket and seal materials etc leave/left much to be desired. The last thing you would want I expect would be seal etc that seep or leak

Synthetics do perform very well in aircooled car engines - Porsche and VWs for example - in your case I would be very circumspect about using one!

 

[roburswest]

Ok..I am officially talked out of synthetic engine oil......no matter how good of an idea it sounds like on paper. Thank you all very much for your input. If I come up with any more oil dilemmas (im sure i will) I will be sure to ask.

 

[Oldwolf]

It would be interesting for you to email Mobil 1 and see what they recommend for your application.

 

[rslifkin]

I agree that a good 15W-40 should do fine. A syth 5W-40 HDEO would work as well, but isn't needed unless the oil is getting very hot.