Oil for Small Block Chevy Airboat

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May 16, 2022
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Looking for some help for an oil for my setup. I have a small block 383, moderate cam & build motor in my airboat. The motor sees 2,800-3,500 rpms when cruising and a healthy dose of 5,5-6,000 rpms. I would like to run an oil that has high zddp to protect it and help with corrosion since it's always near/in water. I ran vr1 20w-50 this weekend but I think it makes too much oil pressure. At cruise it's between 65-70psi and the needle is pegged to 80 max at WOT. I ran the Lucas 10w40 hotrod oil but wasn't impressed. The oil pressure was in a safer range for me (never pegged 80psi)
Can anyone recommend a decent multi weight zinc/zddp 40 wt oil? I've done a ton of research on here and was going to use a diesel oil but apparently they have gotten away from high zinc levels recently. I'm also considering a straight 40wt vr1. I'm in Florida but would prefer a multi weight for when we run in the winter (50-60F). Or is that excessive oil pressure with 20w50 ok?
Thanks y'all appreciate your time!
 
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Just out of curiosity, what didn’t you like about the Lucas?

I believe Valvoline VR1 is available in either a 10W30 or 10W40.
 
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20W-50 is a good choice for your operation. Have you an oil temp gauge? What gives you the idea your oil pressure is too high/ excessive ? How was the engine built?
 
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15w-40 will do just fine. Delvac extreme 15w-40 is great stuff. The cheaper regular 15w-40 is also ok and that's why i use in my sbc's
 

KeySmallBlock

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Given your usage profile, I'd stick w/ the VR1 or try M1 15w-50 w/ a gauge that reads to 100psi:)

20W-50 is a good choice for your operation. Have you an oil temp gauge? What gives you the idea your oil pressure is too high/ excessive ? How was the engine built?
I would love to keep running the 20w-50. I would think over 80psi is too high? At some point it's got to be detrimental. Good thing about an airboat is engine temps aren't ever an issue. It's got an 80 inch fan pulling air over the radiator! My water temp never gets over 190ish. Cruising in the Florida heat is 175-180. I don't have but could add an oil temp sensor.
 
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Looking for some help for an oil for my setup. I have a small block 383, moderate cam & build motor in my airboat. The motor sees 2,800-3,500 rpms when cruising and a healthy dose of 5,5-6,000 rpms. I would like to run an oil that has high zddp to protect it and help with corrosion since it's always near/in water. I ran vr1 20w-50 this weekend but I think it makes too much oil pressure. At cruise it's between 65-70psi and the needle is pegged to 80 max at WOT. I ran the Lucas 10w40 hotrod oil but wasn't impressed. The oil pressure was in a safer range for me (never pegged 80psi)
Can anyone recommend a decent multi weight zinc/zddp 40 wt oil? I've done a ton of research on here and was going to use a diesel oil but apparently they have gotten away from high zinc levels recently. I'm also considering a straight 40wt vr1. I'm in Florida but would prefer a multi weight for when we run in the winter (50-60F). Or is that excessive oil pressure with 20w50 ok?
Thanks y'all appreciate your time!
Valvoline VR1 has high zinc but also additives for high RPM foaming. Tried and true.
 
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Jul 14, 2020
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Looking for some help for an oil for my setup. I have a small block 383, moderate cam & build motor in my airboat. The motor sees 2,800-3,500 rpms when cruising and a healthy dose of 5,5-6,000 rpms. I would like to run an oil that has high zddp to protect it and help with corrosion since it's always near/in water. I ran vr1 20w-50 this weekend but I think it makes too much oil pressure. At cruise it's between 65-70psi and the needle is pegged to 80 max at WOT. I ran the Lucas 10w40 hotrod oil but wasn't impressed. The oil pressure was in a safer range for me (never pegged 80psi)
Can anyone recommend a decent multi weight zinc/zddp 40 wt oil? I've done a ton of research on here and was going to use a diesel oil but apparently they have gotten away from high zinc levels recently. I'm also considering a straight 40wt vr1. I'm in Florida but would prefer a multi weight for when we run in the winter (50-60F). Or is that excessive oil pressure with 20w50 ok?
Thanks y'all appreciate your time!
 

KeySmallBlock

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Valvoline VR1 has high zinc but also additives for high RPM foaming. Tried and true.
This is exactly why I want to run VR1. Would their straight 40wt be ok? I did some research and couldn't find where is too low of temps for startups on straight weight. 60+ degrees is what I'm shooting for.
 
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Any idea the zinc/phosphorus content in it? The delvac extreme sounds promising.
over a thousand ppm on both.

This is what i'm buying right now since home depot sells it and it's currently the cheapest 15w-40 in the market but it's better than the some more expensive ones at other places. it's 10.97 a gal at my local store.

Here's the pqia diesel oil analysis.

Here's delvac extreme.

But truth is even the "worst" ck4 15w-40 will make any decently made sbc rock on till the end of time as long as it gets something of reasonable change intervals. I change the cheap 15w-40 in about 9-11k miles since that's what the olm says. You could also try a euro oil since i run them only when i rarely find them on sale.
 
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Ive been happy running VR1 in the built sbc in my trans-am for years. It has a decent sized cam and no over drive so 3000 on the highway. I would try the 10w30 VR1 and see where that lands you on the oil pressure. Amazon has the 6 qrt case for 31.99 on and off.
 
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Agree with the above post: try VR1 10W30. If you think the oil pressure is too low, mix in some VR1 20W50.
 
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KeySmallBlock

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Agree with the above post: try VR1 10W30. If you think the oil pressure is too lower, mix in some VR1 20W50.
Ive been happy running VR1 in the built sbc in my trans-am for years. It has a decent sized cam and no over drive so 3000 on the highway. I would try the 10w30 VR1 and see where that lands you on the oil pressure. Amazon has the 6 qrt case for 31.99 on and off.
over a thousand ppm on both.

This is what i'm buying right now since home depot sells it and it's currently the cheapest 15w-40 in the market but it's better than the some more expensive ones at other places. it's 10.97 a gal at my local store.

Here's the pqia diesel oil analysis.

Here's delvac extreme.

But truth is even the "worst" ck4 15w-40 will make any decently made sbc rock on till the end of time as long as it gets something of reasonable change intervals. I change the cheap 15w-40 in about 9-11k miles since that's what the olm says. You could also try a euro oil since i run them only when i rarely find them on sale.
I'll try to mix the 10w30 and 20w50 first to get to something that lowers the oil pressure a bit. If that doesn't work I'll try that delvac 15w40. I found a woman calculator on here that can help give expected results. Thanks everyone.
Any other options keep them coming.
 
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This is exactly why I want to run VR1. Would their straight 40wt be ok? I did some research and couldn't find where is too low of temps for startups on straight weight. 60+ degrees is what I'm shooting for.
I recall marine techs liked a straight weight oil. That’s a good start.
 
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Two of my older cars, both with recent rebuilt engines and both running xw50 oils, will pull close to 80psi at high rpms, and you are also assuming that your gauge is accurate.

I would not worry about it.
 

KeySmallBlock

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Two of my older cars, both with recent rebuilt engines and both running xw50 oils, will pull close to 80psi at high rpms, and you are also assuming that your gauge is accurate.

I would not worry about it.
It's a full Stuart Warner gauge and pressure sender. I'll double check that too.
I guess I don't like it maxing out the gauge. 65-70 psi while at 3,000 rpm seems really high.
 
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