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Use the T4 10w30 just to be safe for now.




Valvoline VR-1 is a racing oil that has higher ZDDP levels.




According to them...

Why are zinc/phosphorus levels in motor oil lower in today’s motor oils?

With ever increasing limits on emissions, automobile manufacturers have tightened emission control systems on newer vehicles. This is one of several factors considered when the American Petroleum Institute (API) sets standards for motor oil with zinc. The current API standard is SN, which replaced the previous SM classification. Because phosphorus can poison a vehicle's emission system, the level of zinc is lower for current motor oil. Valvoline uses a new type of zinc/phosphorus that maintains the prior level of wear protection of the engine while reducing the impact on the emission system.


What solutions does Valvoline offer to the zinc issue?

Valvoline offers two solutions to the zinc issue:

  • Valvoline VR1 Racing Oil: Contains 75% higher zinc than SN or SM motor oil with a balanced additive package designed to work in both racing and traditional applications. Valvoline provides this product in both multi and mono viscosity grades: 20w50, straight 50, 10w30, straight 30, straight 40 and straight 60.
  • Longer-Lasting Zinc/Phosphorus: Valvoline uses an advanced zinc/phosphorus additive that keeps higher levels of phosphorus in the motor oil where it protects the engine instead of poisoning the catalytic converter.

Protection of the catalytic converter does not apply to Datsuns as most do not have them. Those that do are used to the higher ZDDP of 40+ years ago. Try to find an oil that has over 1,000 PPM of zinc in it.

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I have become a Mobil1 user, pretty much use it in all of my road car/truck engines anymore. Used to be a Redline guy, but have made the switch simply because all the crate engines I buy come with Mobil1 and the warranties are specific to Mobil1. My tractors and forklift get used Mobil1 (old break in oil) and my Dodge Cummins gets Royal Purple. Even my motorcycles use Mobil1 now. But it's really only because that's what I have laying around the shop.


Point is, engine oil is far less as important a topic as people think it is. The proper grade is more important than anything, as thin oil can effectively lower your oil pressure, and vice versa. Lots of you guys complain of oil leaks on older engines when using synthetic oil, but that has not been the case for anything I own. The "oil leaking past the seals" argument probably has more to do with the grade of oil than the type of oil.


So when I sarcastically said "MOTOR OIL" in my first reply, it's because that's how I feel. It doesn't really matter.


Unless... if the motor is brand new and has a new or reground cam without roller rockers/lifters , that's when the type of oil is very important.

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I tried synthetic ENGINE OIL and my front seal began leaking. Switched back and it stopped after about a month. Used synthetic in my transfer case that was dry, but it began 'seeping', is more like it. Changed the seals (3) and was alright after that. No Datsun made needs synthetic unless it has power adders.

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I fear you are furthering this myth based on very limited personal experience. Not saying you're lying or incorrect, but maybe there were other factors involved.


Check this out - pages and pages of results  - https://www.google.com/search?client=firefox-b-1-d&q=do+older+engies+leak+with+synthetic+oil

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Yes. 30 year old dry seals that were able to contain regular dyno oil but can't handle slippery synthetic. Wetness stopped soon after replacing with regular oil or in the case of the transmission, a new set of seals. The video proves nothing whatever, just a talking head saying it's a myth but has zero experience, and has probably never done an oil change in his life. Your experience is likely with brand new rebuilt engines with new seals. An old Datsun may not always leak but it can. Why anyone would run a synthetic in an old Datsun is beyond me. By the time it needs changing 12-15K???? you've probably put 6 quarts in to keep it topped up. Hell just replace the filter it's got fresh oil in it constantly. The myth about synthetic not leaking..... is a myth.

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You can't know for sure it never leaks on an old engine only that it hasn't yet for you. I only know that it did and I will never do that again. 


27 minutes ago, datzenmike said:

  An old Datsun may not always leak but it can. 


I just remembered I put a synthetic blend in my 620's differential. Yup it began leaking too. Changed the pinion seal and all was well. Maybe all were due to begin leaking? Unlikely. To be fair I did use the same oil in my 710 differential and not leaking. Yet.


This is my experience with synthetic oil and I don't recommend it ever in an older engine.

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Not to beat a dead horse, but new seals fixed your leaks? Sounds reasonable. I'm just pointing out that while you are basing your opinion on a handful of experiences, others have had success over and over again, on a daily basis. So...the numbers don't lie. You can keep telling people that synthetic oil makes your old engine leak, but that isn't wholly accurate, is it?


And per the thicker is better thing, there is some truth to that, speaking in terms of older engines, but it has nothing to do with seals. Older engines generally have loose bearing clearances (by comparison of today's engines), even before they get decades of wear. Thicker oil can "fill the gap" of those loose clearances. When building an engine, I was taught (obviously) to shoot for perfect clearances, but if it wasn't possible (due to block wear or budget or time constraints), a thicker oil would help get the oil pressure up.

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Didn't say it leaks. What I did say was....


On 11/1/2021 at 11:40 AM, datzenmike said:

 An old Datsun may not always leak but it can.



23 hours ago, datzenmike said:



This is my experience with synthetic oil and I don't recommend it ever in an older engine.


20 hours ago, datzenmike said:

Only saying it didn't work for me as an engine oil. Your results may vary. Transmission and differential oils also leaked but new seals fixed this.  


Experience is all we have in this world. How many times have you not listened to popular wisdom and found that your experience of doing something is contrary??? You can only attest to those things you personally experienced. If everyone tells you you're wrong and that something doesn't work, what do you do? agree with them that although it worked for you, you are still wrong???? Sorry, my experience with synthetic oils was that it leaked. I'm glad it worked for you but I will not be persuaded that it does not do what I experienced multiple times.  

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