The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
#1
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Joined: May 2013
Posts: 567
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Car: 1986 Camaro IROC Z
Engine: LB9 305 TPI
Transmission: 700R4
The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
So I own a 1986 Camaro IROC Z with the original factory LB9. In the 6+ years of owning the car, I've always used off the shelf oil (usually Castrol GTX High Mileage or Valvoline Maxlife High Mileage) without a second thought. Recently, I've been reading that flat tappet engines need oil that has more zinc than today's standard motor oil. My car has over 115,000 miles and I want to keep the 305 alive for a little longer. Should I be using a high zinc oil like Lucas Oil's Hot Rod Oil or Comp Cam's Hot Rod Oil? Should I add a zinc additive like Rislone Zinc additive or the STP zinc additive to standard oil?
Have I just been lucky over the last 6+ years with using off the shelf oils?
Have I just been lucky over the last 6+ years with using off the shelf oils?
#2
Joined: Dec 2001
Posts: 9,764
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From: Chicagoland
Car: 1989 IROC-Z. Original owner
Engine: LB9. Dual Cats. Big Cam
Transmission: World Class T-5
Axle/Gears: BW 3.45
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
I use Mobil 1 synthetic on all my cars, but I add a zinc additive on the flat tappet cars, just in case. Probably overkill. Maybe some of the smarter kids can comment.
#3
Thread Starter
Senior Member
Joined: May 2013
Posts: 567
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Car: 1986 Camaro IROC Z
Engine: LB9 305 TPI
Transmission: 700R4
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
#4
Joined: Dec 2001
Posts: 9,764
Likes: 587
From: Chicagoland
Car: 1989 IROC-Z. Original owner
Engine: LB9. Dual Cats. Big Cam
Transmission: World Class T-5
Axle/Gears: BW 3.45
#5
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
Rislone has been one of the long time good products on the market that you just dont hear about. i ran that in all my old flat tappet camed vehicles for years.
You need to check to see if they are still putting the zinc in the Rislone though. havent used in a few good years now.
But yes, you should run an oil with high zinc or a good oil with an additive. On a new engine you will wipe the cam right out without the zinc so why would you not use it after break in on a flat cam? I certainly wouldn't.
You need to check to see if they are still putting the zinc in the Rislone though. havent used in a few good years now.
But yes, you should run an oil with high zinc or a good oil with an additive. On a new engine you will wipe the cam right out without the zinc so why would you not use it after break in on a flat cam? I certainly wouldn't.
#6
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Joined: Feb 2019
Posts: 721
Likes: 168
From: SW Missouri
Car: 1989 Trans Am
Engine: sp357
Transmission: T-5
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
"GM first began installing roller cams in some Chevrolet small-block, V8-equipped cars in 1987. But OE roller-cam installations in trucks didn’t occur until 1995. So, assuming it’s stock with the original, unmodified engine, your 1986 GMC would have a flat-tappet cam. If the engine is broken-in and running fine with the stock, mild cam, high-ZDDP-content oil shouldn’t be needed and could shorten catalytic-converter life (if that’s a consideration in your area). High-ZDDP-content oils are a good idea with hot rod cams that have more aggressive lobes and higher spring pressures than the stockers or as an initial break-in regimen on any newly rebuilt, flat-tappet-cam-equipped engine."
https://www.hotrod.com/articles/pit-...k-roller-cams/
https://www.hotrod.com/articles/pit-...k-roller-cams/
#7
Thread Starter
Senior Member
Joined: May 2013
Posts: 567
Likes: 18
Car: 1986 Camaro IROC Z
Engine: LB9 305 TPI
Transmission: 700R4
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
"GM first began installing roller cams in some Chevrolet small-block, V8-equipped cars in 1987. But OE roller-cam installations in trucks didn’t occur until 1995. So, assuming it’s stock with the original, unmodified engine, your 1986 GMC would have a flat-tappet cam. If the engine is broken-in and running fine with the stock, mild cam, high-ZDDP-content oil shouldn’t be needed and could shorten catalytic-converter life (if that’s a consideration in your area). High-ZDDP-content oils are a good idea with hot rod cams that have more aggressive lobes and higher spring pressures than the stockers or as an initial break-in regimen on any newly rebuilt, flat-tappet-cam-equipped engine."
https://www.hotrod.com/articles/pit-...k-roller-cams/
https://www.hotrod.com/articles/pit-...k-roller-cams/
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#8
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Joined: Mar 2017
Posts: 4,255
Likes: 423
From: Portland, OR
Car: 86 Imponte Ruiner 450GT, 91 Formula
Engine: 350 Vortec, FIRST TPI, 325 RWHP
Transmission: 700R4 3000 stall.
Axle/Gears: 9 Bolt Torsen 3.70
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
Amsoil Premium Protection 10w40, 20w50, or any of their Z-Rod or Dominator oils. We prefer the 15w50 Dominator race oil in our high performance engines. My stock 86 flat-tappet engine I run the Premium Protection 10w40. It is designed with higher ZDDP content for older engines.
GD
GD
#10
Joined: Mar 2014
Posts: 4,480
Likes: 758
From: South Ms
Car: 89 Firebird
Engine: 355 TBI
Transmission: 700R4
Axle/Gears: 10 Bolt.Posi-3.73s
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
Rotella is a safe oil to use with flat tappet engines. It has zinc in it already.
#11
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Joined: Sep 1999
Posts: 2,549
Likes: 680
From: Colorado USA
Car: '83 Firebird (T/A Clone)
Engine: 350 carbed with L-69 components
Transmission: 700R-4 w/2000 RPM stall converter
Axle/Gears: 10-bolt/3.73 ..
Re: The Right Motor Oil for Flat Tappet Engines vs Zinc Additives
Today's motor oils have the same levels of ZDDP that they had in the 1960s. You need more for initial cam break-in.
After that, you should be fine with any off-the-shelf brand of motor oil. If you are running stiff valve springs, you can always mix a ZDDP additive with your oil....
After that, you should be fine with any off-the-shelf brand of motor oil. If you are running stiff valve springs, you can always mix a ZDDP additive with your oil....
Last edited by T.L.; 08-06-2019 at 06:58 AM.
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