Best synthetic for heat control?

[Vwbrad]

Would like some educated input regards the best oil to use in an air cooled alum/magnesium engine, where the primary coolant medium is the crankcase oil, which is forced air cooled re an external cooler(Volkswagen) also a primary concern is proper protection of the flat tappets normally covered by zinc additives that were present in diesel oils (Rotela 15W40)
After some reading on this site, it's my consensus that a good street use oil, would be 5W20, or 0W20 since average oil temps are between 220 to 250 degrees in these engines, was going to use a racing oil till I read this site, will I need to add zinc?, and at what concentration?o

 

[skyactiv]

I think the perfect oil for an air-cooled VW is Shell Rotella T5 Synthetic Blend 10W30. That is unless you want to drive start or drive it in freezing conditions.

http://www.shell.com/rotella/products/t5.html

 

[simple_gifts]

There are non API oils like redline that cover the entire viscosity range that have plenty of zinc.


http://www.redlineoil.com/products.aspx

 

[ChiTDI]

Resistance to shearing sounds like your priority.
Is this an air cooled engine? If so, you may be a little low on the heat estimates.

 

[Clevy]

An oil only needs elevated zddp at break in from new. Otherwise it's not needed. And does that engine have extreme spring pressures that would require extra zddp.
Believe it or not most engines are cooled primarily with oil. Coolant actually cools a smaller percentage of the engine than the oil does.
Anyways I'm using rotella 15w40 in my Harley. It's got a built 106 with 107hp/115tq. That engine gets pretty hot if I'm at a standstill. Mos2 will help with heat too do add a can of that. It reduces friction so with reduced friction less heat is generated.
Use whatever grade the oem specifies. Any of today's offering will be eons ahead of what was originally used and will be fine.
Personally I'd lean towards a synthetic hdeo like rotella 5w-40 or devlac elite 222 0w-40. It would lend itself towards longer drains and resists thermal breakdown more effectively.

 

[ChiTDI]

Reread your post and answered my own question. Sorry.

One school of thought is to to go the other way for heat control.
Lot of dune buggy publications show 15 and 20w50 as the oil choice. Dino as well as syn.

 

[Vwbrad]

If I read the blog on oil university correctly, higher viscosity is not the way to greater oil flow? Since the rule of thumb is ten lbs per thou rpm(standard pres. In a air cooled VW) a 20 weight oil has greater flow at these temps(220plus) than a 50 weight, if I read that right? Greater flow equals more oil on the bearings and hot case.
This engine has been modified for full oil flow thru the pump to an external oil filter not present with a stock engine, so I can further cool if required, I also have head temp monitor as well

 

[Vwbrad]

Does Harley's have flat tappets? Just wondering, I've held a cam shaft, which was installed with high pressure springs, and radical lift/ duration profiles, valve stems oval'd within 1500 miles of operation, and cam lobes had uneven wear indicated by mic. That engine was run with 15w40' I had supposed the wear was a result off excessive spring press. And the removal of the zinc due to cats being installed on the new diesel trucks?

 

[bmwtechguy]

Use heavy enough viscosity to maintain adequate oil pressure when at normal operating temps for your ambient weather. Air cooled engine oil temps vary more with ambient air temp changes than water cooled engines do. A 0W-20 or 0w30 might be great for winter use up there in Canada, but hot summer use might require something heavier like 5W or 15w40 or even a 15W or 20W-50. If you want an excellent oil with moly already in there, then Schaeffers is worth a look, if you can find it. They have a very shear stable 5W-50 oil that has extra zinc/phosphorous. That might be one that could cover more operating temps for that engine. I use it in highly stressed BMW applications and it has done very well for last several years.