10-40 or 20-50 in 73' C20 350 Block?

[Spool]

Hi guys.

Heard a few different things on this and made the move to 20-50.

What oil do you use in your original engine block and why?

-Thomas

 

[bucket]

10/30 normally. If an engine tends to burn a little oil, I use 10/40. There's been one or two worn out motors that I have run 20/50 in.

 

[Spool]

Thanks for your response.

I've ran 10-40 in my truck since I've had it, 2 years.
There were no signs in upping the oil thickness performance wise but a few different people from professional engine builders to other classic car owners said to run 20-50.

I just made the switch to 20-50 and it feels fine, given it's only been a day.
But was this a mistake?

The idea was with a block, cam, piston being 44 years old and now running on oil with a lack of zinc and phosphorus, I should use a thicker oil to protect what little has worn away over the years.

Is this rubbish?

 

[Rusty Nail]

10w-30 because that's what it was made to have in it. I do not know better than The General and I never built engines or sold trucks for a living.
Is it rubbish? ..... It's not for me, doowutchyalike.

God Bless America.


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[Spool]

10/30 normally. If an engine tends to burn a little oil, I use 10/40. There's been one or two worn out motors that I have run 20/50 in.

Bucket,
Is there any harm in running 20/50 in my motor as a proactive measure?

 

[1987 GMC Jimmy]

Well, ****. I've put 5W30 in everything that's a gas burner. My two, my mom's '02 Burb, my grandma's Pontiac... That's what the caps say on all of them so I just do it. Is the slightly thicker 10W30 better in the long run?

 

[bucket]

Bucket,
Is there any harm in running 20/50 in my motor as a proactive measure?

Beats me. While it may not hurt anything, it may not help anything either. My thoughts are that if it runs well on 10/30 and doesn't use excessive oil, then 10/30 is fine.

Well, ****. I've put 5W30 in everything that's a gas burner. My two, my mom's '02 Burb, my grandma's Pontiac... That's what the caps say on all of them so I just do it. Is the slightly thicker 10W30 better in the long run?

A lot of newer stuff calls for 5/30. I have a few that call for it, but only one (my '00 Burb) gets it. They are all much older than the Burb.

 

[1987 GMC Jimmy]

I gotcha. I'll switch over as I do oil changes. It gets below 20*F where I am in Mississippi maybe once a year so I don't necessarily need a thinner oil.

 

[87scotty]

i run 15w40 delo in my old oil burner she dosnt complain to much! i know personaly a boss of mine who put 350 thousand miles on an old 350 running 15w40 swepco since the day he bought it!

 

[CSFJ]

20-50 seems a little excessive for a stock engine. If it's the zinc content that's causing the worry, there's always 15w40 rotella. I've been running that in an '88 chevy 350 for a couple years now and it seems happy with it.