What is the best oil viscosity to run in a 292 Inline-six with high miles?

[Jonathonmb357]

My C30 has over 96k miles, and the 292 six under the hood currently has 40 weight Valvoline race oil in it, but it's time to change it out. I've had someone tell me that too thick of a viscosity may wear out the oil pump quicker, but I'm not sure.
What's the best oil viscosity for an old engine in the midst of the constant weather changes of Texas?
It might freeze over and snow in a few months, but after spring, the summer gets upwards of a hundred degrees.
I would appreciate any advice!

 

[SquareRoot]

Any 5w/40 or 10w40 will be fine as long as it has high zinc for your flat tappets. It may be easier to use an additive if you can't easily find the high zinc oil. I use VR1 10/30 here in southern Arizona. Oil will not hurt your oil pump regardless of viscosity.

 

[Midnightmoon]

I don't do it personally, but years ago, I knew a few people that ran conventional diesel oils such as 15w40 Rotella T or Mobil Delvac for their higher zinc levels. Now that most of the diesel oils have gone through marked changes in recent years, I can't comment on if those zinc levels are still higher than equivalent gas spark ignition oils.

 

[Jonathonmb357]

@SquareRoot Thank you so much! That makes a lot of sense.
If I choose a conventional 10W-30, I need a zinc additive?

 

[Jonathonmb357]

@Midnightmoon Oh well thank you anyway! I appreciate it.
That's pretty cool though.

 

[WFO]

I just changed to this Castrol high zinc conventional oil a couple of weeks ago.

Amazon.com

 

[Matt69olds]

You could run any 10w40 oil in that. I’m pretty sure even when new the valve springs are pretty weak, the springs havent improved with age, the engine has had decades to establish a good wear pattern, not to mention the oil manufacturers have been slowly eliminating zinc for years.

If your a better safe than sorry kind a guy, you ca t go wrong with the Valvoline racing oil.

 

[Paladin]

Get a Holley!!!! Opppps........wrong thread again, damn it!!!! LOL

 

[SirRobyn0]

Well I think for me it would depend on how the engine is behaving. That motor called for 10W30 from the factory and even though it is high mileage if it's not burning a lot of oil, your not seeing blue smoke and there isn't any internal clatter I'd stick with 10W30, or 10W40, if you live where it gets really cold 5W30 or 5W40 would be fine as long as it covers at least the 10W30 range. If you're having an issue and you'd like to prolong a rebuilt either running 20W50 or substituting a 1/2 or full quart of hyper luber with a 10W30 oil would be fine.

Though you didn't ask someone brought up zinc, and we can go though the pros and cons of high zinc oil, but the generally accepted rule of thumb at most shops that deal with old rigs, is if it does NOT have a high lift cam, is not used hard and is broken in, then high zinc oil is unnecessary and honestly could be harmful in the long run as high zinc racing oils are lower in detergents, so that could result in sludge / excessive wear. If you haven't been running high zinc I would not switch to it.

What I'm doing I'm running a heavy duty 15W40, in my gas 305, why, because it's a little higher zinc than gas oil (no where near the content of racing oil), my 305 is stock, uses a little oil, plus I run it fairly hard when towing my trailer, but also commute in it. So I feel like it is good compromise for me and my driving conditions. It's also a fairly universal oil as it is rated for both gas and diesel engines. So most of the farm equipment my square and my Dodge can run it.

Thanks my thoughts hopefully there is something helpful for you in there.

 

[SirRobyn0]

I don't do it personally, but years ago, I knew a few people that ran conventional diesel oils such as 15w40 Rotella T or Mobil Delvac for their higher zinc levels. Now that most of the diesel oils have gone through marked changes in recent years, I can't comment on if those zinc levels are still higher than equivalent gas spark ignition oils.

They are still higher than gas. Most gas oil is around 800PPM, most diesel oil is around 1,000 - 1,200PPM though it does vary those figures apply to most 15W40's fall in that range but most of the newer formula lighter diesel oils have lower zinc levels.

Gas engine oil back when these vehicles were made was depending on the year in that same 1,200ppm - 1,000ppm range. Racing oil is often over 2,000ppm, some even high than that. No need for that unless your engine is built with high lift cam and stiff valve springs.

 

[Grit dog]

I’d just use conventional 15w40. But then again, like Franks Red Hot, I use that sht in everything!

 

[Jonathonmb357]

@SirRobyn0 Thanks! I sure did learn a bit from your advice! I pretty much have all the info I need now. lol

 

[Jonathonmb357]

I appreciate everyone's input, it's awesome
I don't think I'll ever second guess what oil I need anymore

 

[Jonathonmb357]

You could run any 10w40 oil in that. I’m pretty sure even when new the valve springs are pretty weak, the springs havent improved with age, the engine has had decades to establish a good wear pattern, not to mention the oil manufacturers have been slowly eliminating zinc for years.

If your a better safe than sorry kind a guy, you ca t go wrong with the Valvoline racing oil.

Thanks! I'm definitely a better safe than sorry guy. This truck is my muse!

 

[80BrownK10]

My C30 has over 96k miles, and the 292 six under the hood currently has 40 weight Valvoline race oil in it, but it's time to change it out. I've had someone tell me that too thick of a viscosity may wear out the oil pump quicker, but I'm not sure.
What's the best oil viscosity for an old engine in the midst of the constant weather changes of Texas?
It might freeze over and snow in a few months, but after spring, the summer gets upwards of a hundred degrees.
I would appreciate any advice!

96k is not high miles. You sure it's not 196 or 296? I'd say 40w is too thick unless it's worn out. I'd go with 15w 40 diesel oil . Starts in cold easy and plenty thick for hot weather.