viscosity

[JT68]

Right Daryl, except climate affects not only engine start up oil viscosity, but actual engine operating temperature. The outback or southern desert is a very different operating temp than Northern Canada, Quebec or Alaska. In southern climates an oil cooler may be useful to maintain normal oil temps especially while racing, but running in the North, your oil may not even get to normal operating temps and an oil cooler would be silly. My point was that at the actual underhood operating temps in the south, 20/50 is plenty viscous and (more importantly) you should warm up the engine to operating temp before pushing it very hard. Not sure why anyone would be running 20w50 in a domestic 454??

15w-50 is probably a nice compromise for the US/hot temps.

This is spot on:

"Ambient Temperature
Although environmental temperature does not add to the heat your engine generates during operation, it impacts oil viscosity. This is the reason your location is so important in selecting which oil to use.

Between a 10W-30 and 10W-40, 10W30 motor oil would run smoother in colder climates while a 10W40 would be more effective in preventing engine wear and tear in warmer temperatures."

"What is 10W 30 oil recommended for?
10W-30 motor oil is recommended for ambient temperatures not exceeding -30°C/-22°F in the winter or 35°C/95°F in the summer. This is a great motor oil to use if you live in Canada or cooler U.S. states.

Colder regions would require 5W-20, while hotter regions may call for 10W-40/20W-50"

[JT68]

Like I said, 30 and 40 wt oils are perfectly suitable and great for most climates. Decades of street and track experience says 20w50 works fine in roadster engines that were designed in the early 60's. The quality of the lubricants is probably more important though, especially for cam wear.

Last time I checked, roadsters don't have hydraulic lifters, VVT or modern gerotor oil pumps-those design constraints which are applicable to modern engines simply are not relevant for roadster engines. If roadsters had hydraulic lifters, it might matter.

Some guys like Rotella 15w40, I've used that too on street cars, but I think the Mobil 1 has a bit more zinc and Mobil 1 has been superb in all the engines I have ever used it in(in my actual experience). Some of the Redline products are outstanding as well, based on our actual use. Brad Penn took over the old Kendall green oils, and those were great dino oils (Studdard's 1987 championship car was running Kendall 20/50 fyi)

I prefer 40or50 running wts because the slightly higher viscosity provides additional wear/cushion/film protection for the steel on iron wearing parts in these older engines. (same reason 90wt is used in diffs) There is no need for 20/50 up in the north and something thinner at startup is probably better-certainly in MN lol.

You can certainly run whatever oil you like, it doesn't matter to me. I'll get back to you on the long term experience with 15/50 Mobil1 in a few years. Hope this helps.

[Daryl Smith]

Here is a good write up with a chart to help in your decision....The chart must mean 'start-up' temp as running temp will exceed 100*C and all oils will have to protect past that temp.

https://www.motorstate.com/oilviscosity-htm/

I thought the post on page 4, 5th post by RDY4WAR was very interesting....
https://www.speed-talk.com/forum/viewto ... 4&start=45
" The Red Line HP 5W-30 is within 0.1 cP of Mobil 1 Racing 0W-50 (3.8 cP), a 30 grade welterweight boxing with the heavyweights. "
There is a lot in that post to digest:
1) Dynamic film thickness
2) High Temp High Shear (HTHS) test @ 300*F

A search for 'optimum oil operating temp shows differences on different websites. Motor Trend says 230* - 260*F (110-127*C), another says 100* - 110* C
(212* - 230*F). These are operating temperatures, which, if your cooling system is working properly, will not change - regardless of your location/climate - well below temps all oils are tested to. YMMV.

I don't believe hydraulic lifters enter the equation, the biggest factor is the flat (non-roller) lifters. Not sure what that equates to on the U20 engine, as I've never seen any mention of using high ZDDP oils with OHC engines.... If you know of a site that addresses this, please post a link.

I think the biggest factor is the use of the car, whether road race, autocross, hard street, or just 'toodling' around. Pick your poison! 10W-30 is the recommended oil from the factory, 20W-50 has been used in these engines for many years without problems. Your choice. I'm certainly not going to second guess your reasoning. The information is out there for an informed choice if you decide to pursue it.

You can use whatever oil you decide on, our interpretations of available data may be different, that's fine with me. My interpretation is that with the quality of the oils available today, the trend is to a lower viscosity oil, for power, milage, and protection - for all engines, not just modern ones.

[Daryl Smith]

From Classic Motorsports site:
https://classicmotorsports.com/articles ... ecord-str/

Q. Do you recommend using a zinc additive in older engines?

A. Engine oils are a very precise balance of additive components and base oil(s) that work in harmony to provide the desired lubrication. The introduction of any type of additional additive disrupts this formulation synergy–like jamming an extra piece in a puzzle that’s already complete. This change in harmony can have a negative effect on the performance of the oil, not to mention change its identity.

Bottom line: Additional aftermarket additives are not needed. Frankly, if an end user relies on an additive to change some aspect of their oil’s performance, then they’re using the wrong oil.

KENNETH M. TYGER
Director of Technical Services Penn Grade
PennGrade1
Lubricants

A. We never recommend using aftermarket oil additives. Engine oils are designed with a fine balance of base oils and additives designed to work holistically to provide optimal protection and performance. A properly formulated oil for the intended application doesn’t require aftermarket additives to provide good protection. In fact, adding aftermarket additives can disrupt the oil formulation and reduce protection.

LEN GROOM
Technical product manager
Amsoil

A. No! If your oil needs an additive to properly protect your engine, then you need a different oil.

LAKE SPEED JR.
Certified lubrication specialist
Driven Racing Oil

[JT68]

All good Daryl. one notable addition:

"the biggest factor is the flat (non-roller) lifters. Not sure what that equates to on the U20 engine, as I've never seen any mention of using high ZDDP oils with OHC engines...."

Most OHC engines (especially modern ones) use different mechanical configurations or rollers that are much easier on the cams than the U20, so U20's are certainly not specifically addressed by oil companies. The U (and L) were copies of the 50's/60's Mercedes design and the point loading is extremely high-especially with HD valve springs and increased lift from Nissan. The U20 cam set up is extremely demanding on the rockers which is why the original chromed-Merc design failed miserably(Nissan was definitely pushing the cam and spring specs).

The u20 cam/rocker interface is just about worst case scenario for sheer/oil/loading so High zinc oil is certainly recommended. Much higher rocker loading, heavier valves and very similar loaded surface areas as the R, just upside down and on top of the head...

I also agree that good quality oils (but not the el cheapo bargain basement stuff) these days are probably as good as the premium oils from 30 years ago- the additive packages are very much improved. That combined with better metallurgy and manufacturing from the OEM's make some motors capable of 400,500k, 1M miles with careful service. Most roadster engines originally didn't make 75k without surgery. The 2J 98 Lexus300SC I sold at 380k running Mobil1 never used oil and was never opened up except for timing belts. pretty remarkable. That is great design, great manufacturing, great metallurgy, great oil.

Additional zinc additives should not be needed with the right oil.

[mikeb]

JT wrote:

15w-50 is probably a nice compromise for the US/hot temps.

Just to echo Jim re viscosity, I have a friend who ran Nissan Motorsports back in the day and Ed Pink Racing before he retired a few years ago. He highly recommended Driven HR1 conventional 15W-50 hot rod motor oil. It's a little spendy, but there's another option to consider.

Also, re oil temp: I was running an oil cooler in hot Southern California traffic in the mid 1980's (daily driver street car driven pretty hard) and the oil never reached normal operating temperatures. Not a good thing, so I ended up removing the oil cooler.

Mike

[Gregs672000]

Regarding adding zinc additives, the same warning about messing with the wear reduction package by adding them was demonstrated on Bob the oil guys website, where oils frequently performed LESS effectively WITH additional zinc products that as formulated. It's not just how much zinc, its how the whole package works together. That's why I chose the Hyper-lube non zinc product (not the viscosity motor honey stuff) because it didn't mess with the zinc package. Unfortunately it has been discontinued due to Rislone buying them out. I still have a couple bottles. I have experienced cam and rocker wear with pitting on both, with the cam having been broken in correctly. Today I have lighter valves with the same springs with a higher lift cam and NEW rockers (not now, but originally matched to the cam) and no wear issues. Is that the new rockers? The lighter Valves (same springs though so...)? The additive? 20/50 VR1 oil? I tend to think it's the new rockers and a good high quality high zinc oil... Maybe the Hyper-lube... didn't hurt. Just glad it's gone.

[JT68]

This is probably a waste of time, but here is another completely different way to look at things that is hard to argue with, no matter what oil brand or weight you believe in or personally prefer:

a. in 2023, it would be impossible to conduct any type of statistically significant and meaningfully scientific analysis of oil types or viscosities or both in datsun roadster engines. It would be impossible to have a statistically valid sample of identical roadster engines, operated under identical environmental and or/multiple environmental conditions with randomized oil choices. Other engine experiences simply don't apply-there are just too many differences and variables. Many are similar, none are exactly the same.

b. because of a, it is statistically and scientifically impossible to prove that any 10,20,30,40 or50 weight oils result in ANY improvement of wear, life, economy or any other benefit to a roadster engine with a particular oil. No matter what our personal bias.

additionally, it would be impossible to statistically and scientifically prove that any alleged, purported, completely hypothetical shortcoming of any reasonable oil choice is actual fact when operating in a roadster engine. Forget about cavitation, waxing, sheer failure, startup wear, wear because of heavier pump loading, reduction of wear due to additional "flow", reduced friction on wearing surfaces, cooler operating temps. Forget about all these things that we might be passionate about. They can't be proven in a scientific way in Datsun Roadster Engines. (yes, Mobil or Shell or Chevron could conduct such testing on 1000 Honda engines, for 100's of millions of dollars, but not even the oil companies could do valid testing on roadster engines.- the sample size is just way too small.

c. because of b, we are left with the anecdotal, or empirical experience of long time users. My data might be right, or wrong same as every other emperical source, but the longer the years and the higher the number of engines observed, the better the confidence intervals. Regardless, the CI's are still extremely poor due to small sample size and variable conditions, so statistically these observations are meaningless.

Some folks might say (have said), yes, but modern engines all run these lighter new oils and that is 100% true. So many cars now run 5w20, 0w20 etc. THOSE NEW engine designs have fundamentally different designs than the 60's roadster engine. They use different oil pump designs, run extremely tight clearances, have optimized everything with extremely low fiction wearing surfaces and just about everything is lighter. Most of this was directed at efficiency, emissions AND optimizing performance to offset economy, but either way, ALL modern engines are extremely different than 60's builds. It's completely apples and oranges.

So, while I personally prefer a thicker oil cushion for the cams and rockers, yes that thicker oil does require a tiny bit more energy to pump etc. I'm comfortable with the wear results I've seen over the past !40! odd years, but I certainly can't prove it was exclusively because of 20/50. As Greg pointed out, it could have been a myriad of variables that contributed to the results- careful builds, high quality oil, high quality parts, frequent oil changes, lack of abuse, and so on. 10/30 MIGHT have performed just as well, but it is doubtful that it could have performed any better.

So, these days, if I lived in Minnesota, I'd run a high quality 10/30 or 40. Down south, I'm currently using Mobil 1 15/50 with great results so far. That is just my opinion as is everything else on this thread-there simply is no valid scientific or statistical data that is applicable.

[drieseck]

OK gentlemen thanks for all the inspirational enthusiasm and valuable explanations. As a novice in comparison, boiling down this dialog to an informed decision (for me)-------this was very helpful: "So, these days, if I lived in Minnesota, I'd run a high quality 10/30 or 40. Down south, I'm currently using Mobil 1 15/50 with great results so far."

I do appreciate a spirited push-n-shove as much as the next guy/gal especially from those with chops (JT, Daryl, Greg---occassionally redroadster). While it will take me another two weeks to read all the references provided (thanks Daryl), with my projects I've come to value ----countless times---40yrs experience (thanks JT). Please know I have now gleaned more information from both contributions here ----much appreciated; and including Greg, and so many other times: Curtis, premo, Steve, Pat and --------------occasionally redroadster.

Cooling this down (since GA and BC seem to be hot as hell according to my map) selfishly, these discussions are important for my continued education. As my project(s) evolve I have become better informed using this forum and your on-going guidance(s). In that light, I'm offering a quencher. If you guys are ever through Hood River, I'm buying cold beer. Thanks again for the passion.

[rwmann]

From memory, Kendall 20W/50 was the 1970s go-to oil, replaced by various synthetics in the 1980s. I settled on Redline lubricants, front to back, and haven’t wavered. That said, I’m not stressing the U20 and drivetrain as above.

[redroadster]

No JT oils are worse , because the Pennsylvania grade is gone , used up .
what's the other grade ,the name escapes me ?

As far as babit bearings it makes sense that more flow is better than less right ? There will be much less with 50w oil so unless you have an engine with large clearance bearings like many racing engines are which BTW will often blow up during a season ( but gave you better perf during that short racing period, that's why ) Ive said ,50w should last longer on splash oiling ,valve stems , cyl walls when it's doing 100 strokes per sec. And arguably better on chains / sprocket wear ...but it thickens in the engine and racing engines start by drilling out oil galleys / passages
Other than those 2 things which are of the extreme 10w40 is as good , better at flow , esp cold
Remember what trash Penzoil became after the Penn grade was gone

[JT68]

Brad Penn. I've used it a few (recent) years with only good results, but it has to be ordered(Summit), so the Mobil1, ValvolineVR1 or Rotella is much easier to find.

Seems to be good and they have 10/30 and 40 as well:

"In 2015, D-A Lubricant Company, Inc. acquired the Brad Penn Finished Lubes division — including the iconic PennGrade 1 High-Performance Oil — from
ARG, the former Kendall refinery in Bradford, Pennsylvania"


I've had excellent results with all the Redline products too. Again, just my opinion, hope this helps!

[Gregs672000]

https://www.chevelles.com/threads/inter ... st-3673078

This may help. Go specifically to response #11 and hit "more" ... it will open up this huge list of oils tested etc and his reasoning as to what oil does what.
Probably won't continue to run 20/50 once I'm out of my current supply. He shows results of adding zinc to oils... not a good idea!