Synthetic Engine Oil?

[stever]

Is there any reason why one should not use synthetic motor oil in a BJ8 engine? I am wondering if there are any seals or gaskets that would not be compatible with synthetic oil. I have heard that "older" engines may be susceptible to leakage when using sythetic oil due to seal/gasket incompatibilities. Also, is anyone aware of any other potential problems with using synthetic? I use synthetic in my other family autos. My BJ8 engine has less than 20,000 miles since overhaul/rebuild. Thanks!

 

[Dave Russell]

Steve,

I think that you have answered your own question. The Healey engine design is not particularly oil tight even when in new condition. Poor seals & gasket materials.

The only way to know for sure is to try it & see what happens. The synthetic won't damage anything, maybe just leak more & cost a lot to buy.

I don't think there is much to gain.

D

 

[Jerry]

I did an experiment in my car with Synthetic. I was trying to see if it maintained the oil pressure better under high heat conditions. I think during this last summer's use, I would say it did have a higher heat resistence. All other oil properties are probably the same. If you can buy them on sale, they are not too expensive. I had two for one coupons at Kragen.

Jerry

 

[CDK]

The biggest problem when picking a lubricant seems to be how do you tell just how well it works. I spent some time racing and building my own motors, this gave me the oppertunity to use different oils and measure the wear to internal components.The results were very interesting. In my opinion synthetics are the best in reducing if not eliminating friction wear and heat.Heat being probaly the worst thing to all component life spans. There are many different types of synthetics ,full polymer-resin being the best. I am holding back giving any set brand names.Beaware there are dfferences.Alot of people do mention price,but then how much does a motor or transmission cost in comparison. I have used synthetics for over ten years with excelent results in all types of aplications, if it takes lube I have put synthetics in it.I even had a old timer (65 years) in the Automatic Transmission rebuild world talk me into trying Synth motor oil in one of my automatics,three years later every thing is working great.Try small experiments at first untill you feel confident.

 

[RF Thom]

Petrolium based engine oils break down at 280 degrees F. where as synthetis break down at 450 degrees F. Oil in the engine serves many functions one of which is a heat transfer medium, and as such can reach temperatures of 260/275 F. Petrolium based engine oils therefore do not provide a sufficient protection cushion. Remember the hotist components in an operating engine are 1st the valves then the pistons. Exhaust valve can reach 1800 degrees F. - pistons domes 450 degrees F. As the oil breaks down it turns to a black ash, [ remember 'Blacky Carbon']and is commonly found behind the piston rings eventually contaminating and stopping them from functioning. I use synthetic oil in all my vehicles. Before I retired I was a Design Liaison Engineer for GM Powertrain and had access to relative test results. I've seen data where 600 hour dyno tests [ = 100,000 miles ] without an oil change with oil sampling analysis every 25 hours showed no trace materials after the initial 10 hour breakin.

Regards, Bob

 

[BEEJAY7]

Bob..
Very interesting comments. Were there any signs, inthe test data, of gasket or seal wear?

Cheers

 

[littlecars]

Well Stever I work in an industrial Plant and have a couple words that may or may not apply but its food for thought. My plant uses a fairly good sized air compressor 150 HP, 750 cfm, it runs 24-7 and runs on synthetic oil the compressor runs great, however when we went to this type of oil some of the seals in the equipment reacted to the oil and swelled causing the valves, and seals in the cylinders to stick. like when you get mineral oil into a brake system. Changing to a different seal material took care of this problem maybe this wont affect automotive seals good luck
Dale

 

[RF Thom]

Reply to BeeJay7

There were no leaks at any seals or gaskets. As a side note the testing was run at wide open throttle with load controlling the engine speed fluxuating from peak torque to peak H.P. back to peak torque over a five [5] minute cycle. The engine temperature is controlled with a submerged radiator and oil cooler in a water tank. Coolant runs at 220 F. [under 14 PSI pressure] and oil at 280 F. The exhausts turn cherry red and require external fans to keep the solid. Sort of like climbing a mountain, pulling a trailer, with you foot on the floor and you can't get above 30 MPH.

I am currently running 20-W50 Castrol Syntec in my Healey and MBG and have not noticed any significant wicking or leakage increase.

Regards, Bob