HDEO in Older Cadillacs

[SlantyNW1990]

My Dad has a Fleet of Vintage Cads,aswell as my brother.One is a 66 with a 429 v8,the other is a 61 convertible with a 390 v8,and the last one is a 74 eldo conv.with a 500cid v8.

Now my dad swears by Castrol GTX 10-40 and a STP filter and has been running it in his 74 for over a decade now,even when it was his daily driver.but i think they all can benefit from a HDEO...Am i right?or should i put rotella in the older ones and leave the 74 alone?

 

[Rock_Hudstone]

Modern passenger car SM/SM grade oils are woefully low on ZDDP levels which flat tappet engines need to survive.

On the other hand, some argue the relatively low valve spring pressures on stock non Hi-Perf engines don't require high ZDDP content.

However, why prove the point by wiping out a few cam lobes when HDEO oils are widely available and no more expensive than PCMO. The older engines could also benefit from the higher detergent levels as well.

 

[maybehabitformin]

I wouldnt run anything thicker than 10w30 just not needed, I would run 5w30 myself.STP filters are OK there are a lot better filters for the same money or a couple dollars more.Castrol GTX is a good oil I have had good luck with it.You could use HDEO if youd like with no issues.

 

[Chris142]

These old engines didn't have much oil pressure at idle. A too thin of an oil may let the oil light flicker when fully warmed up and idling in gear. Id go with 15w40 in all of them myself.

 

[Jakegday]

Originally Posted By: Rock_Hudstone
Modern passenger car SM/SM grade oils are woefully low on ZDDP levels which flat tappet engines need to survive.



This. I run Rotella Triple Protection 10w30 in my older vehicles for this reason.

 

[mongo161]

These old engines didn't have much oil pressure at idle. A too thin of an oil may let the oil light flicker when fully warmed up and idling in gear. Id go with 15w40 in all of them myself. [/quote

+1....Chevron Delo, Shell Rotella, Castrol Tection Extra, Mobil Delvac, Valvoline Super Blue, Kendall Syn blend with Titanium, Motorcraft HDEO, NAPA store brand, WM store brand or the new kid on the block Mag 1.....all are great oils in 15w-40.

Just find the one on special and use it......IMO....they are all about the same.

 

[maybehabitformin]

If any of those motors need 15w40 to keep the oil light off they need bearings

 

[hemitom]

between my brother and myself we have had many big block mopars from the 361 to 440, and we always ran valvoline 10w40 in them,we then switched to 15w40 . The engines just seemed to run better and quieter on the hdeo and consumption was reduced in all engines also. No scientific proof here just my own observations.

 

[dnewton3]

ZDDP is often misunderstood and the hype of its importance often overblown.
http://www.blackstone-labs.com/Newsletters/Gas-Diesel/November-1-2010.php
I'm not saying that we can ignore it; but it needs to be put in perspective.
The absence of ZDDP does not infer wear will go sky-high. Wear can be averted by other chemical means. Improvements in base stocks and also other additives (Ti, for example) can otherwise help in controlling wear.

And let's not discount the tribochemical barrier that is a MAJOR player in the wear reduction efforts. See SAE 2007-01-4133 for details.


Generally, I think a PCMO in 10w-30 would do well here. You can use an HDEO; it certainly won't hurt the engine.

I am not super familiar with those engines; do they have any known Achilles heel?

The lack of Pb in fuel (which was present back when those cars were made) is likely to hurt the valves/guides long before you wear out main or rod bearings anyway.

 

[SS1970chrysler]

Originally Posted By: hemitom
between my brother and myself we have had many big block mopars from the 361 to 440, and we always ran valvoline 10w40 in them,we then switched to 15w40 . The engines just seemed to run better and quieter on the hdeo and consumption was reduced in all engines also. No scientific proof here just my own observations.

Same here. We also had a few older Caddy's. 15w-40 or 10w-30 in HDEO will be just fine.

 

[Garak]

Originally Posted By: Jakegday
I run Rotella Triple Protection 10w30 in my older vehicles for this reason.

I would consider this to be a rather sensible choice. However, as Dave Newton points out, the ZDDP issue is overblown. I lean towards wanting a higher ZDDP oil in vintage applications, but when you look at the oils of yesterday, many of them are well within modern phosphorous limits, and some actually had substantially less ZDDP than a modern PCMO.

The 10w-30 HDEO suggestion makes good sense. It's not ridiculously expensive. It's readily available. Its viscosity matches the application. It has sufficient ZDDP.