Hey guys so this will be the first oil change on my cj5 since I've owned it for 4 months I honestly don't have a cle how many miles it has on it but o know ig has had a few previous owners anyway I need to know what number oil and what brand to use thanks in advance -Donovan
donovan53
Its all a matter of preference. I run either mobil delvac or rotella 15-w40 in everything I own
10/30 was the standard when the 304 was new.
Synthetic is a good upgrade for below zero weather.
And I am very jealous !!
If you have the clutch with a 3speed that is my all time favourite Jeep.
And the last new Jeep I drove off the showroom floor was a '74 CJ5 with the 304.
Congratulations !
Synthetic is a good upgrade for below zero weather.
And I am very jealous !!
If you have the clutch with a 3speed that is my all time favourite Jeep.
And the last new Jeep I drove off the showroom floor was a '74 CJ5 with the 304.
Congratulations !
The Jeep Factory Service manual specifies for 10w-30 or 10w-40 in warm weather, and 5w-30 in cold weather.
The brand of oil you use does not matter. Synthetic oil is not necessary.
The brand of oil you use does not matter. Synthetic oil is not necessary.
Any motor oil customer service folks will advise to go with the manufacturer's recommendations.
The 1974 CJ5 service manual, page B2, recommends
for ambient temperatures above zero F, use SAE 10W-30 or 10W-40
For ambient temperature below zero F page B2 ,recomends, SAE 5W-20 or 5W-30
In 1974 the motor oil specification was SE. This specification was used for 1979 and older gasoline engines.
This motor oil specification is now obsolete. This oil contained high levels of ZDDP( zinc & phorphorus) additive to properly lubricate the contact surface between the flat bottom tappets( hydraulic & solid type) and the camshaft lobes.
The current motor oil specification, SN, contains much smaller concentrations of ZDDP.
There is some controversy about the lower concentrations of ZDDP causing wear damage of the camshaft.
High performance engines with higher valve spring pressures are more affected than stock engines.
The ZDDP concentration was reduced because it was discovered the compound plugged up the catalytic converters.
Most motor oils found on the shelf today for gasolines engines are formulated to the SN specification with lower concentrations of ZDDP.
However, the weights of the oil are still valid from 1974 CJ5 service manual, page B2.
To reduce the oil usage of the engine selecting a muti grade oil with a higher high temperature viscosity rating will help.
For example a 10W40 oil will use less oil than a 10W30 oil. The down side is the 10W40 oil will contain more viscosity index improvers than the 10W30. As a result, the life of the oil will be reduced.
However, the modern so called "diesel motor oils" still contain high concentrations of ZDDP.
Shell/Rotella T is one of these oils and is very popular for folks wih flat tappet lifter engines, like the 1974 AMC 304 V8.
Modern diesel oils have the CJ-4 specification.
Also, racing oils such as Lucas, valvoline, redline, royal purple have high concentrations of ZDDP since these oils are formulated to be used in high performance engines.
I use Valvoline racing oil, straight SAE 30, since my CJ5 is not started at ambient temperatures < 50F.
Increasing high temperature viscosity rating does not increase oil pressure.
The 1974 CJ5 service manual, page B2, recommends
for ambient temperatures above zero F, use SAE 10W-30 or 10W-40
For ambient temperature below zero F page B2 ,recomends, SAE 5W-20 or 5W-30
In 1974 the motor oil specification was SE. This specification was used for 1979 and older gasoline engines.
This motor oil specification is now obsolete. This oil contained high levels of ZDDP( zinc & phorphorus) additive to properly lubricate the contact surface between the flat bottom tappets( hydraulic & solid type) and the camshaft lobes.
The current motor oil specification, SN, contains much smaller concentrations of ZDDP.
There is some controversy about the lower concentrations of ZDDP causing wear damage of the camshaft.
High performance engines with higher valve spring pressures are more affected than stock engines.
The ZDDP concentration was reduced because it was discovered the compound plugged up the catalytic converters.
Most motor oils found on the shelf today for gasolines engines are formulated to the SN specification with lower concentrations of ZDDP.
However, the weights of the oil are still valid from 1974 CJ5 service manual, page B2.
To reduce the oil usage of the engine selecting a muti grade oil with a higher high temperature viscosity rating will help.
For example a 10W40 oil will use less oil than a 10W30 oil. The down side is the 10W40 oil will contain more viscosity index improvers than the 10W30. As a result, the life of the oil will be reduced.
However, the modern so called "diesel motor oils" still contain high concentrations of ZDDP.
Shell/Rotella T is one of these oils and is very popular for folks wih flat tappet lifter engines, like the 1974 AMC 304 V8.
Modern diesel oils have the CJ-4 specification.
Also, racing oils such as Lucas, valvoline, redline, royal purple have high concentrations of ZDDP since these oils are formulated to be used in high performance engines.
I use Valvoline racing oil, straight SAE 30, since my CJ5 is not started at ambient temperatures < 50F.
Increasing high temperature viscosity rating does not increase oil pressure.
Agree, AMSoil Z-ROD full synthetic motor oil with high concentration of ZDDP required for classic & high performance vehicles is on the prefered list.
AMSoil is guaranteed to maintain properties for one year in the engine, with engine not used & storaged, which is typical for classic vehicles.
Believe the shelf life on modern motor oils is ~ four years, because the additives deteriorate with time.
Shell/Pennzoil states this fact in the literature.
I always check the date stamp before buying motor oil. Sale oil could be out dated.
Some recent research indicates that so called "full synthetic oil" can actually use group 3 base oil, which is natural crude oil based.
"The national advestising dept of the better business bureau ruled that group 3 base oil can be considered "synthetc" because modern oils made using hydroisomerization technolgy have most of the same performance features of early synthetic"
Most convenional motor oils are group 2 based. There is a wide range for group 3 base oil stock. API uses the viscosity index to classify base oil categories.
The problem with group 3 base oil products is the viscosity index can be as low as 121, while the viscosity index range on group 2 base oil is 80 to 120.
The higher the viscosity index the more stable the viscosity is at elevated temperaures.
True synthetic motor oil is group 4 base oil which is poly-alfa-olefins (PAO) made from small molecules.
Mobil oil patented an improved PAO process and began to market the prduct as Mobil 1.
Shell/Pennzoil platinum & ultra platinum, full synthetic motor oil , uses the new GTL process, gas-to-liguid, but is classiified as a group 3 base oil , since it is synthesized from natural gas.
AMSoil is guaranteed to maintain properties for one year in the engine, with engine not used & storaged, which is typical for classic vehicles.
Believe the shelf life on modern motor oils is ~ four years, because the additives deteriorate with time.
Shell/Pennzoil states this fact in the literature.
I always check the date stamp before buying motor oil. Sale oil could be out dated.
Some recent research indicates that so called "full synthetic oil" can actually use group 3 base oil, which is natural crude oil based.
"The national advestising dept of the better business bureau ruled that group 3 base oil can be considered "synthetc" because modern oils made using hydroisomerization technolgy have most of the same performance features of early synthetic"
Most convenional motor oils are group 2 based. There is a wide range for group 3 base oil stock. API uses the viscosity index to classify base oil categories.
The problem with group 3 base oil products is the viscosity index can be as low as 121, while the viscosity index range on group 2 base oil is 80 to 120.
The higher the viscosity index the more stable the viscosity is at elevated temperaures.
True synthetic motor oil is group 4 base oil which is poly-alfa-olefins (PAO) made from small molecules.
Mobil oil patented an improved PAO process and began to market the prduct as Mobil 1.
Shell/Pennzoil platinum & ultra platinum, full synthetic motor oil , uses the new GTL process, gas-to-liguid, but is classiified as a group 3 base oil , since it is synthesized from natural gas.
High level of ZDDP is for high performance engines, and that pretty much rules out any stock Jeep engines. If you feel higher levels of ZDDP may be beneficial, Rotella is good, or add some STP to whatever oil you have.
All three of my Jeeps use whatever everyday oil is on sale. Synthetic oil is an unnecessary expense for a low tech engine.
All three of my Jeeps use whatever everyday oil is on sale. Synthetic oil is an unnecessary expense for a low tech engine.
been running 10W-40, any name brand that is on sale every 5,000 miles, for 50 years now and have never had an engine issue on any of my vehicles. And I drive them til the bodies rot off.
My last Grand Marque 4.6 went 385,000 miles on it and was running strong when my grandson wrapped it around a tree.
My last Grand Marque 4.6 went 385,000 miles on it and was running strong when my grandson wrapped it around a tree.
The stock AMC 290-304-360-390-410 V8 has valve seat pressure = 89# and open valve seat pressure = 200# with new stock spec. springs.
An Edlebrock high performance cam with stock valves and springs will have a valve seat pressure = 132# and open valve seat pressure = 312#
Current SN motor oils still have dialyldithiophosphate(ZDDP) additive between 600 ppm to 830 ppm compared to the older SE spec motor oils (1979 & older) with ~ 1400 ppm ZDDP.
When looking at the cut away of the new Ford F150, 3.6L V8 at the auto show, it incorporates flat bottom buckets in direct contact wth the camshaft lobes. The open valve spring pressure is probably much less than 200#.
This geometry is very similar to a flat bottom hydraulic lifter riding on the camshaft lobe.
To be safe would elect to use a motor oil with ZDDP concentration equal to the SE motor oil specification that was used on the vintage flat bottom hydrulic lifter style engines.
Valvoline racing oil, VR1 has ZDDP = 1400 ppm zinc & 1300 ppm phosphorus.
Depending on how the CJ5 is used, short trips, long haul highway, snow removal, rock climbing, dirt trails, etc. I use my CJ5 as a tractor for plowing & cultivating dirt farm fields at low speed.
Short trips & extended idle time usage is considered servere duty. For this type of service would use 20W50, if starting above freezing ambient temperature. If starting beween 0F/32F, would use 10w30 motor oil.
If starting below 0F would use 5W30 motor oil.
An Edlebrock high performance cam with stock valves and springs will have a valve seat pressure = 132# and open valve seat pressure = 312#
Current SN motor oils still have dialyldithiophosphate(ZDDP) additive between 600 ppm to 830 ppm compared to the older SE spec motor oils (1979 & older) with ~ 1400 ppm ZDDP.
When looking at the cut away of the new Ford F150, 3.6L V8 at the auto show, it incorporates flat bottom buckets in direct contact wth the camshaft lobes. The open valve spring pressure is probably much less than 200#.
This geometry is very similar to a flat bottom hydraulic lifter riding on the camshaft lobe.
To be safe would elect to use a motor oil with ZDDP concentration equal to the SE motor oil specification that was used on the vintage flat bottom hydrulic lifter style engines.
Valvoline racing oil, VR1 has ZDDP = 1400 ppm zinc & 1300 ppm phosphorus.
Depending on how the CJ5 is used, short trips, long haul highway, snow removal, rock climbing, dirt trails, etc. I use my CJ5 as a tractor for plowing & cultivating dirt farm fields at low speed.
Short trips & extended idle time usage is considered servere duty. For this type of service would use 20W50, if starting above freezing ambient temperature. If starting beween 0F/32F, would use 10w30 motor oil.
If starting below 0F would use 5W30 motor oil.
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