As far as an oil answer, any 10W40 should do just fine. As most has said above, if you change your oil regularly then dino is much cheaper than syn. For me, I'm a Castro fan but have read a lot here on the Forum about the Rotella. Since my wife's and my Chevy HD's use the Rotella stuff, maybe I'll try some of it and see how my hot rod likes it. Personally I don't think I'll see much difference in the short term.

 

As an aircraft mechanic who enjoys his shark. let me just say that comparing a gasoline reciprocating engine (SBC 350) to a jet or helicopter engine (turbine) is absurd and shows little true knowledge on the topic.

In a gasoline reciprocating engine, the oil is contaminated by combustion gasses every time the engine runs. Remember, the oil coats the cylinder walls where the fire happens! Therefore, this oil becomes so contaminated at some point it must be changed to prevent damaging the components in the engine it is designed to protect. Also. these engines generally see 5-6,000 rpm, maybe a little more. so the lubricating qualities of petroleum based oils are more than adequate. Syntehetic oil will become just as contaminated as petroleum based oil.
If you have a racing engine that regularly turns in excess of 8,000 RPM, synthetic oil may be right for you.

In a turbine engine, the oiling system is not contaminated by combustion gasses, in fact it is protected from such contamination. Therefore,the oil will last much longer than in a reciprocating engine. Also, a turbine engine operates at incredible RPMs, 30,ooo plus. Therefore the superior lubricating qualities of synthetic oil are necessary to protect the rotating components.

In my humble opinion, while synthetic oil will work in an older engine, it is not worth the money and if the engine is not a fresh rebuild, I would strongly recommend staying away, as in all likeliehood, it will cause the oil consumption rate to increase dramatically.

Clean oil is the lifeblood of our Shark engines. There have been many posts regarding cams that have gone flat, contaminated engine oil can be one of those causes. Stick to petroleum based oil, change it regularly and enjoy driving your shark for many years.

 

I've used Mobil 1 in my 2000 Chevy Pickup truck (350 engine) since about the 6,000 mile mark, with no problems. Since I only put about 4500 miles a year on it, I change it every spring. Haven't had to add any oil between changes. I bought a 1995 Jeep Wrangler a couple of years ago, with @ 75,000 miles on it and only use dino oil in it. Any buildup of wax or carbon on the older seals would be "cleaned out" by the synthetic oil (which is known for doing that), and cause leaks.
In a new or rebuilt engine,synthetic is fine. Not so with an engine with 50 K miles or more. The multi grade dino oils are fine for all older engines. Just pick a heavier oil if you have higher summer temps and want higher oil pressures.

 

For those that prefer the higher anti-wear additive package allowed by the API for diesel oils, you can get synthetic diesel oils that have the benefits of synthetics and the higher anti-wear additive packages. AMSOIL makes several:
AMSOIL Series 3000 Synthetic 5w30 Heavy Duty Diesel Oil
AMSOIL SAE 15w40 Heavy Duty Diesel Oil
AMSOIL Synthetic Blend 15w40 Diesel Oil

There are many myths circulating regarding synthetic oils and seal leakage. Due to the significant variation in synthetic oil base stock, blanket statements about synthetic oils and seal leakage may be inappropriate. Many synthetics have a highly processed petroleum basestock. Others such as AMSOIL and Mobil 1 have a PAO basestock, which tends to shrink seals. And yet others, such as Redline use an ester basestock which tends to swell seals. Most synthetics contain higher levels of detergents, which will clean sludge from seals exposing them to oil.

If you have a clean engine and you are experiencing no leaks, then you should not have any leaks with AMSOIL. On the other hand, if the engine contains sludge due to age or inappropriate maintenance practices, you may experience a temporary leak. When the seals have gone for sometime without oil contacting and nourishing the seals due to blockage from sludge, they will harden and shrink. Since AMSOIL contains a significant amount of detergents, it will clean and remove this sludge exposing dried out seals to the oil. This leakage should only be temporary, since the AMSOIL contains Ester which will improve the seal’s suppleness and counters the shrinkage of the PAO basestock. Based on reports I've read, AMSOIL should swell the seal 3% to 5%. But, if the seal has a mechanical fault, such as a crack or tear, then AMSOIL can't repair the damage.

 

actually, synthetic oils are only used in turbine aircraft, which really have nothing to do with our reciprocating engines. add to that the fact taht the turbine oil and commercially available automobile synthetics have nothing in common and you come upon a sweet myth


nearly every reciprocating aviation engine is a dino oil machine works well even with cylinder head redlines around 400F

 

and of course, i post that from page one having not read the A&P's input on page two

 

I have worked on Navy and Marine F-18's, F-14's, AV-8's, EA-6's, H-60's, UH-1's,AH-1's, and H-53's for many years now ........................Wow..I'm jealous..especially with regard to those choppers..... [/QUOTE]