Old Chevy 305 oil recommendation

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Jan 8, 2013
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23
Location
Austin, TX USA
Hey oil gurus

I bought an old 81 Square body truck

Been working to restore it, fired it up the other day, it sounds decent, but i hear a bit of a tick even after i reset the valve lash

It had been sitting a while and the previous owner had a massive leak on the passenger side valve cover, and I'm guessing he was just refilling it

I live in central Texas (Austin) so normally it's relatively hot, just looking for a good recommendation for a higher mileage older motor

I had been thinking to run some conventional Rotella or T6 in 5w40 and see if the engine noise goes away

Any input is appreciated
Thanks!
 

captainofiron

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captainofiron

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Old 305’s have problems with the cams going flat. In a warm place like Tx, I’d run a good 15W-40 and not look back.
I'm not really sure how many miles this thing ran, looking under the covers i was surprised how clean it was, I'm thinking due to the leak it was always running low, I was thinking the T4 10W30, but yeah maybe 15W40
 

MolaKule

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When I had a 305 in a van many years ago, I ran 10W30, usually the latest Pennzoil flavor.

The only problems I had with it were the short life of plugs (~ 30k) and an exhaust manifold leak which gave a ticking sound.

Even with all of the ancient smog control devices on it, the engine went to over 250,000 miles when I sold it.

Addendum: Just remembered one other thing. Our 305 had an air pump, as one of the ancient smog control devices, that made a ticking sound as well before I replaced. it.
 
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captainofiron

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When I had a 305 in a van many years ago, I ran 10W30, usually the latest Pennzoil flavor.

The only problems I had with it were the short life of plugs (~ 30k) and an exhaust manifold leak which gave a ticking sound.

Even with all of the ancient smog control devices on it, the engine went to over 250,000 miles when I sold it.
Ah that's a thought maybe it's the manifold

I didn't see any soot trails but it's so oily under there from the valve covers maybe
 
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The only success stories surrounding a 5.0L I'm familiar with is removing it from the chassis and replacing it with anything other than another 5.0L.

However, they do seem to run forever, even when neglected. It's the modern version of the old Slant-Six. Yours even has the same oil bath down the side of the block.

I agree with the others; a 15w-40 HDEO, dino version would be my choice.
 
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10w-30 anything was it, at least for taxi fleet use, 200-600 miles/shift, two shifts a day.
They would stretch the timing chain & jump time before they would do anything else bad. : (
Gotta love a small block Chevy never allowed to cool down!! Yeah!
 
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I discovered something!

The radiator cap isn't tightened properly. The center wing on the radiator cap is supposed to line up with the overflow expansion hose.
 
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Whatever xW30 or xW40 is on sale at Tractor Supply, Menards, or Wal-Mart. 15w40 tends to be the cheapest and will work great. I wouldn't worry about detergents too much as that engine looks spic and span inside from your pic.

I assume when you mentioned setting the "valve lash" you meant adjusting the lifter preload? A 305 will have hydraulic lifters and will want a three quarters turn of the nut past zero lash. If you adjusted it like solid lifters, you'll probably hear all kinds of funky noise.
 
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I run 10w30 for the winter months but in the summer with triple-digit heat, i'll go with a 10w40 up to a 20w50, either one would be good for that tired 305, this is the snake pit on my 83 smog monster. ;)
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