synthetic fluids???

[DJK]

Are modern synthetic lubricants suitable for use in these vehicles?  Having resealed the rear diff., axle seals inner and outer, transmission  also, just wondering what to use.

[Tooljunkie]

Although the new fangled lubricants are far superior to what was used back in the day, tolerances are so much different also. Rear end lubricant, in my opinion would be ok, but i can almost guarantee you will notice more noise. Personally i dont see any gain in using a more expensive lubricant.

gentleman came into shop with a box full of synthetic  lubricants For his 90’s diesel chevy. Rear diff,front diff, transfer case and manual  transmission all got synthetic oil. 
one month later he returns, to have synthetic replaced with conventional fluid. Everything was howling he said. Could hear it over the noisy diesel. 
it was from there on i didnt use synthetic unless it was called for. 
 

engine oil, for our older engines, we need the proper additives to maintain the bearings. Most synthetics dont have enough zinc 

for one. 

[DJK]

How about 80w-90 GL-5 for the rear diff and 75w-90 GL -4 for the trans.? My manual calls for straight wts. according to ambient temp., modern lubes are multiple viscosity. Vehicle will only be used during summer time.

Edited April 21, 2020 by DJK
change

[Sam Buchanan]

If you have a manual transmission with a clutch:

 

I use 75W-90 GL-4 in the diff of my P15. I started out with the same in the trans but the 1st to 2nd shift was crunchy until the trans got hot. It seems the modern lubricants are too "slippery" to allow the 'mature' synchronizers to function as designed.

 

I changed trans oil to Redline 70/80W MTL and the transmission now shifts smoothly at all temps. This is a case where more friction is better and the Redline won't degrade the brass synchronizers. The Redline costs more than the stuff off the shelf at Autozone but it should outlast me. Two quarts will fill the transmission and leave plenty for any topoffs needed in years to come.

Edited April 21, 2020 by Sam Buchanan

[DJK]

I was at NAPA this morning, their fluids show GL5 and GL4 ratings in the same fluid. From what I remember GL4 is for trans and GL5 for rear diff.

Thanks for the info Sam, I will get some Redline ordered.

[DJK]

This is from Redline website: 

75W140NS GL-5 GEAR OIL

• Contains extreme pressure additives like our 75W140 GL-5 oil, but lacks friction modifiers to balance slipperiness
• Popular for historic and vintage transmissions, like Mid-1930s to early-1950s synchro-equipped gearboxes in cars and trucks
• Helps with noisy or rough shifting in troubled A-833 Dodge/Plymouth 4-speed transmissions from 1964 to 1969
• Option for noisy transmissions when mixed with 75W90NS or MT-90 to bring viscosity level up
• Also used in clutch-type limited slip differentials in racing for maximum lock up-some users add Limited Slip Friction Modifier in small doses to customize slippage
• Non corrosive formula, safe for use with all synchro materials

[Sam Buchanan]

This is the one you want for a manual transmission, it replaces GL-1 80W that was spec'ed in the old manuals:

 

 

https://www.amazon.com/Red-Line-Transmission-Transaxle-Lubricant/dp/B000CPCBEG

 

 

Edited April 21, 2020 by Sam Buchanan

[DJK]

Thanks Sam, just ordered 2 qts.

[lepic56]

I use AMSOIL SEVERE GEAR® 75W-90 IN THE DIFF, 

As for the transmission  THE SHOP MANUAL RECOMMEND,,  VISCOSITY SAE 10-W , so I use  Amsoil Transmission Fluid SAE 10W..

as for the engine you need high content zinc ,, I heard that SHELL ROTELLA AS ZINC FOR DIESEL ENGINE, Myself, Quest what??,, yes Amsoil 10w30  Z-ROD Synthetic Motor Oil is specially engineered for classic and high-performance vehicles. A high-zinc formulation to prevent wear on flat-tappet camshafts and other critical engine components, along with a proprietary blend of rust and corrosion inhibitors for added protection during long-term storage.

 

 

[Sam Buchanan]

My comments above were for a manual transmission where the old manuals called for a heavy gear oil (GL-1 80W).

 

A well-regarded high-zinc engine oil that I found when looking for such for the VW Beetle (flat tappets) is Valvoline VR1 Racing oil:

 

https://www.amazon.com/Valvoline-10W-30-VR1-Racing-Motor/dp/B00DJ4FMK2

 

But I run Walmart's store-brand 10W-30 in my P15's 218.....I don't want it to develop an attitude........   ?

 

Edited April 21, 2020 by Sam Buchanan

[Sniper]

Additives are needed in some amount for a flat tappet cam.  The higher the spring pressure the more it's needed.  Our engines have virtually no spring pressure, look up the specs. 

 

40lbs closed, 110 lbs open for a 218.  Stock 2bbl 318 is 83 lbs closed, 178 open and I've been running my 318 on whatever oil is on the shelf for decades.  I haven't had my 218 for decades but it's running off the shelf oil. 

 

If you were running a 7000 rpm race engine with a .650" lift flat tappet cam you should worry about it.  With our engine what's in the latest oil specifications is adequate.  roller cams, hydraulic or solid are less prone to issues because the tappet rolls on the lobe rather than slides across it.  Bearings ride on an oil film so if your clearances are right there is no metal to metal contact, if they are off and you have metal to metal, well that's how bearings spin and no amount of additive will fix that. 

 

Final thoughts, if you want to run an oil with more additives, it will not hurt.

 

 

[DJK]

Thanks guys for all the good info.

[plymouthcranbrook]

On 4/21/2020 at 7:50 AM, Sam Buchanan said:

If you have a manual transmission with a clutch:

 

I use 75W-90 GL-4 in the diff of my P15. I started out with the same in the trans but the 1st to 2nd shift was crunchy until the trans got hot. It seems the modern lubricants are too "slippery" to allow the 'mature' synchronizers to function as designed.

 

I changed trans oil to Redline 70/80W MTL and the transmission now shifts smoothly at all temps. This is a case where more friction is better and the Redline won't degrade the brass synchronizers. The Redline costs more than the stuff off the shelf at Autozone but it should outlast me. Two quarts will fill the transmission and leave plenty for any topoffs needed in years to come.

I have had the same problem ever since I got my 52. Crunchy shifts into second unless done slowly or trans hot. I put it down to a worn syncro. Will replace with Redline and try.Thanks for the idea.

Edited April 24, 2020 by plymouthcranbrook

[plymouthcranbrook]

5 hours ago, Sam Buchanan said:

My comments above were for a manual transmission where the old manuals called for a heavy gear oil (GL-1 80W).

 

A well-regarded high-zinc engine oil that I found when looking for such for the VW Beetle (flat tappets) is Valvoline VR1 Racing oil:

 

https://www.amazon.com/Valvoline-10W-30-VR1-Racing-Motor/dp/B00DJ4FMK2

 

But I run Walmart's store-brand 10W-30 in my P15's 218.....I don't want it to develop an attitude........   ?

 

Farm and Fleet oil for mine.  And everything else s well. Never a problem oil related. For years.(40 years)

[BobDeSoto]

I've been using 30W non detergent and a lead additive in a 51 DeSoto engine.

 

Can I safely switch to the Amsoil synthetic Z Rod 10W-30?

 

Is it also non detergent?

 

 

Edited April 23, 2020 by BobDeSoto

[greg g]

GL 1 is recommended for manual transmission. Later spec stuff is not brass and bronze friendly. Eventually will degrade synchro parts made of those metals.

[Sam Buchanan]

1 hour ago, greg g said:

GL 1 is recommended for manual transmission. Later spec stuff is not brass and bronze friendly. Eventually will degrade synchro parts made of those metals.

 

Red Line MTF is a replacement for GL1 and won't degrade the brass stuff.

[BobDeSoto]

22 hours ago, BobDeSoto said:

I've been using 30W non detergent and a lead additive in a 51 DeSoto engine.

 

Can I safely switch to the Amsoil synthetic Z Rod 10W-30?

 

Is it also non detergent?

 

 

 

[keithb7]

For most of us with a few old cars that we drive for pleasure use on fair weather days,  we may never see the long term benefits of dialing in the best oil for our needs. We read, and can easily get caught up in all the oil lab test results, or the marketing statements from scientists. In reality, it would take a large fleet of cars running 24/7, all with oil analysis testing being done regularly. Components torn down and the time of overhaul and some type of deep wear analysis performed to determine what oils are right for each component, for our fleet. There are several variables that can determine which oils to use. Oils have different additive packages to address some of these variables. Some variables can be addressed such as operating temperatures, thermostat, radiator temperature drop, seal up engine leaks, maintain good valves seals with valve sets, operator behaviours such as warm up time, engine RPM's,  acceleration, are only a few examples. We cannot really control mother nature's ambient temperatures. Where we live is a factor. The closer to the equator, generally the hotter it is year round obviously. Our land contours can lead to accelerated oil degradation. For example living in a mountainous area the car's components may be stressed further over long periods of time. Compared to a car driven on the great plains. The longer that the oil runs hotter, it leads to further breakdown, oxidizing sooner.  Driving your car hard up a steep hill for 20 mins everyday, your oil choice could make a difference.

 

In my opinion some of these variables are why there is no formal consensus on what is the "best oil" for our cars. A large vehicle fleet putting on tons of miles, with controlled testing, with facts and teardown results could help you answer that question. The individual car owner, here and there, driving? Not likely. Synthetic oil in an old car? My .02 is it's a bit of a waste of money. Just my opinion.

[Sam Buchanan]

35 minutes ago, keithb7 said:

Synthetic oil in an old car? My .02 is it's a bit of a waste of money. Just my opinion.

 

Yep, change out that store-brand 10W-30 every year or so......whether it needs it or not...........    ?

 

Our inexpensive oils are far superior to what was available when our cars were new.

 

Edited April 23, 2020 by Sam Buchanan

[lepic56]

23 hours ago, BobDeSoto said:

I've been using 30W non detergent and a lead additive in a 51 DeSoto engine.

 

Can I safely switch to the Amsoil synthetic Z Rod 10W-30?

 

Is it also non detergent?

 

 

Amsoil ZROD is a detergent oil also,, My engine in my 52 Plodge (230cu,in,) was rebuilt by the former owner,  I don"t know what kind of oil he used and how many milles since rebuilt, not that many anyway..  

 I bought it last September and switch right away to Amsoil Zrod  10w30,  (should had open the side valves covers to check for Gunk before).  it run great, oil pressure is good and does not smoke but it leak some.. as it was before Amsoil..   after 200 miles the oil is turning black some, so it doing it job of cleaning I quest!! 

After the storage seasons is over,, in May, I will try Amsoil  engine flush, before the next oil change,  see what's going to happen??

It could be an interesting topic to fallow,,, isn't it??

 

[plymouthcranbrook]

On 4/21/2020 at 5:14 PM, plymouthcranbrook said:

and Fleet oil for mine.  And everything else as well. Never a problem oil related. For years.(40 years)

Wonder what I wanted to say  here?

Edited April 25, 2020 by plymouthcranbrook

[T120]

On 4/23/2020 at 8:56 AM, Sam Buchanan said:

 

 

......  "Our inexpensive oils are far superior to what was available when our cars were new."

 

_ Sure about that? ?

 

[Sniper]

I don't think any synthetic oil is also non-detergent.

[T120]

I've been using straight 15/40 conventional motor oil in my older vehicles,(summer driving), off the shelf - nothing fancy. Not one of them has a freshly rebuilt engine.I've had the oil pans off,cleaned out sludge and just general maintenance and things seem okay. Something to keep in mind if you decide to switch to a synthetic motor oil, a minor drip of oil from the engine may  become a bit more of a nuisance.?

Edited April 24, 2020 by T120