Switching to synthetic after 33 years. Any red flags? AQ200D (Chevy 305)

[1981fiberform]

So I am the caretaker of the old family boat which still runs great. In fact it runs just like it did 30 years ago - when it is warm - but if it hasn't been run for a few weeks it is an ornery mutha to get warmed up at the ramp. So I am wondering instead of 10W40 conventional if I switched to a 5W40 or 0W40 Synthetic so the oil was not as thick when the engine is cold if it would warm up easier? Has anyone had good or bad experiences trying this?

 

[bruceb58]

You shouldn't be running 10W40 conventional oil in the first place.

15W50 Mobil 1 would be a good choice for synthetic.

 

[GA_Boater]

If the engine runs as good as it did 30 years ago, obviously it ran poorly 30 years ago. Your warm-up troubles may be telling you something about the condition of the engine. I think she could be getting tired and needs freshening, which may be as simple as a carb rebuild, possibly more. Changing to a different oil won't fix that. My opinion.

 

[bruceb58]

+++1 ^^^

Your warm up problems are likely becuase your choke isn't adjusted properly.

 

[doyall]

... Changing to a different oil won't fix that. ...

Agreed.

 

[Thalasso]

Sometimes there are problems switching to synthetic in older motors. Especially ones that are 30 yr's old. The gasket will start leaking.(oil pan. Front and rear seals). The gaskets aren't made to take synthetic oil.

 

[Thalasso]

Sometimes there are problems switching to synthetic in older motors. Especially ones that are 30 yr's old. The gasket will start leaking.(oil pan. Front and rear seals). The gaskets aren't made to take synthetic oil.Your better off staying with what you have been using.

 

[doyall]

Sometimes there are problems switching to synthetic in older motors. Especially ones that are 30 yr's old. The gasket will start leaking.(oil pan. Front and rear seals). The gaskets aren't made to take synthetic oil.Your better off staying with what you have been using.

Most of today's synthetics are not the type of oils that will cause that nature of problem. The Group III and III+ mass-marketed, reasonably-priced 'synthetic' oils are highly refined mineral oils that have similar performance characteristics of the higher-priced 'man-made' oils. If you do not use a Group IV, or especially a Group V, oil (PAO or ester based) there should be no cause for concern.

 

[MikDee]

Well, your engine will now run cooler, smoother, and more efficiently then ever.

 

[1981fiberform]

Thanks for all the feedback! I think I had heard before but forgot about the seals can leak with old motors if you switch to non-mineral based oils. That is a significant downside for a boat that leaks no oil. My other thought with synthetics was to extend time between changes. My neighbor has two cars with 400k+ miles and he changes the Mobil 1 annually I run it in my newer cars and change at 10K intervals.
However, it looks like my risk vs reward is pretty poor on this one. (probably not warm up easier, maybe cause an oil leak,vs. change the oil less) So I will probably just run another season on the Volvo recommended 10W40 that has worked for 33 years. As for the rough warm up, it really is a one time deal. Went to the lake for 5 days with scouts and it started as soon as I turned the key every time except that first day at the ramp.

 

[bruceb58]

So I will probably just run another season on the Volvo recommended 10W40 that has worked for 33 years.

Volvo never recommended that viscosity oil for your engine.

This is from a factory Volvo service manual a few years newer than yours but same block. See that it specifically says not to use the oil you are using.

 

[captmello]

the Volvo operators manual recommends 10w-30 or 10w-40 for that era V-8. To me, it doesn't sound like you use the boat that often. change the oil once a year.

 

[Tail_Gunner]

A better choice would be delo diesel oil, it has zinc and would clean up that old girl a bit.

 

[Tail_Gunner]

https://www.google.com/search?q=del...ww.bobistheoilguy.com&espv=2&biw=1061&bih=814