56 Buick

Which engine oil grade to use with 56

Recommended Posts

Hi all

 

So the owners manual for the 56 says to use a SAE 10W-30 grade oil. That seems thin to me and I wondered what others are using?

 

Especially also given fuel now does not contain the lead additives it once did.  The engine in my car was apparently rebuilt around 2010 but there is no way to know now how much of the engine was reconditioned and whether they altered the valves, etc. to take account of unleaded fuel.

 

Thanks

 

Drew

 

Share this post


Link to post
Share on other sites

I'll keep it short..I run castrol gtx 10-30 year round no problems... Nailheads don't really need the lead or hardned seats in fact they can cause major problems do to coolant passages right by the valve seat.. Mine does have hardned seats but that was done before I got it.. And no problems 

Share this post


Link to post
Share on other sites

My '54 is very happy with Shell's Rotella T  oil.   It has additives more like the oils intended for the Buick, including good amounts of the zinc needed to protect the valve guides.

Share this post


Link to post
Share on other sites

Weight of the oil is dictated by bearing clearances. Too thin and it will shear & it won't do the job. To thick and it can’t get into where it needs to be and it won’t do its  job. Heavy oil also puts more stress on the oil pump drive. 

 

The ONLY reason to go heavier is if the engine is significantly worn and you have low oil pressure. 

 

Additives are a completely different story. You need ZDDP (aka zinc phosphate) in the oil to keep from destroying the cam & lifters. 

 

Ignore everyone who cites a brand preference, and look at actual oil specifications. API SN spec won't cut it in these engines. CJ-4 spec (often marketed as diesel oil) will. If an oil meets both, that’s fine. CI-4 is ok, but not as good, CK-4 is insufficient. Beware of labels that cite “CJ-4 compatible.” That’s not the same as “equivalent.”

 

Or just buy an SN spec oil and add a ZDDP additive. 

 

For in depth info, start here:

 

http://www.widman.biz/English/Selection/Oil.html

Share this post


Link to post
Share on other sites

"Short answers" above.  "Longer answers" below  . . .

 

Oil viscosity?  I believe you'll find that as the ambient temps cool and stay that way, thinner oils were recommended, town to "10W" viscosities.  More about oil flow at initial start-up than anything else.  Same engine thermostat temps as warmer climates, so operating temps were ultimately the same.  Depending upon engine wear, oil consumption might have been a little greater, but that might be more dependent upon the style of scraper on the oil rings and valve stem seals/guide clearances.

 

Most people usually ran "30" motor oils back then for "Above 32 degrees F" temperatures.  Using thicker oils in warmer climates could have worked if the internal clearances had wear on them, but a band-aid fix at best.  In some of the much higher temp regions, "40" oil might have worked best, BUT that was when an oils level of protection tended to be related to its viscosity rather than the oil's base blendstocks and additive package.  NOT that way, nearly to that degree, any more.

 

As for zddp levels, I believe that Old-Tank has been using Castrol GTX motor oils in his '55 Buick for many thousands of miles with no valve train wear issues.  Zddp issues didn't really exist in the times when the Nailheads were designed (in the early '50s).  It was not until the earlier '60s when longer duration camshafts with higher valve lift levels and much stiffer valve springs (to allow for 7000rpm in NASCAR engines) that cam lobe wear issues needed the higher levels of zddp.  Of course, nobody talked about it back then, either, except hose involved in building those engines.  PLUS oil was usually changed much more frequently!  So that's when zddp levels started to increase and many used STP Oil Treatment to compensate for any weakness in their oil's toughness against wear.

 

The cam lobe wear issues surfaced first from the engine rebuilder industry.  The OEMs use a thicker Parkerizing surface treatment on their cam lobes, but the aftermarket cam makers probably didn't, such that the normal cam installation paste lube and GM EOS were sufficient lube to get the cam lobes past their first 30 minutes of run/break-in time.  When the zddp levels were decreased, THEN their corner-cutting showed up.

 

"SL" oil was the last oil spec that many tend to agree as having enough zddp in it.  Those oils were 1000ppm zddp, which is also where the synthetic SL oils that VW recommends for their car diesels which run the fuel injection pump off of one cam lobe.

 

Mobil1's "Turbo Diesel Truck" 5W-40 oils usually were spec'd at 1000ppm of zddp, but Rotella T and Delo 400 "dino" 15W-40 oils usually had more like 1400ppm, initially.  Same with their synthetic 5W-40 oils.  Now, with tighter diesel emissions, it's more like 1200ppm, but still well past the "SL" oils' 1000ppm.

 

GM still builds crate motors with flat tappet camshafts in them.  I looked in the engine installation instructions (which are also available online) for one of their 427 Chevy engines a few years ago.  I was not surprised to see that their oil recommendation was "SM" motor oil (the spec at the time I looked).  BUT they are dealing with OEM-level cam Parkerizing surface treatment of the cam lobes and valve lifters of specs they built themselves.  These engines are run on a test stand after being built, as production engines were, so their lobes are lubed and a known motor oil is run through them, and they are initially run in a controlled environment.  So, it all works.  Once the cam gets past that initial run-in period, the cam/lifter interface is much slicker and the need for higher levels of anti-friction compounds is greatly reduced.

 

I have a copy of the paper GM did to validate the use of "SM" oils in flat tappet engines.  They used the weight loss from the valve lifters to gauge wear levels.  Surprisingly, these wear levels were very similar to those with "SL" and prior oils.

 

Perhaps the BEST place to look at oil analysis (used and unused "virgin" motor oil) is www.bobistheoilguy.com,  click on "Oil Forums" and then on "Virgin Motor Oil Analysis".  Participants post independently-done oil analysis for various motor oils, unused virgin oil, which details the level of additives in the oil, its viscosity, and sometimes the TBN and TAN levels.  

 

Most of the modern "SN" and "SM" oils have 800ppm of zddp.  The prior "SL" oils were at 1000ppm zddp.  The "diesel-spec" oils (Rotella T 15W-40, for example) were at 1400ppm zddp.  The more recent diesel oils are closer to 1200ppm zddp, due to emissions regulations.  Their TBN is also slightly lower, too.  By comparison, the Amsoil Synthetic "Z-Rod" oil is about 1400ppm zddp.

 

One of the changes in the most recent diesel oil specs is that the TBN of the oil has been lowered, for some reason.  Ford didn't allow its use in their new PowerStrokes for a time, but now do.  I haven't researched to see what the deal was with that.  Higher TBN means that the oil can absorb more acidic combustion by-products before the TBN reaches "2.0", which is when most fleet administrators who use oil analysis to gauge when to change motor oil, desire to change their fleet's oil.  That meant, in one case, oil change intervals were decreased from 25K miles to 22.5K miles.  All depending upon how the vehicle is used and how many cold start cycles happen.  Some engines are harder on motor oil than others, both in oil contaminants and how soon the oil "shears" out of its original viscosity range.

 

Zddp is the most visible anti-wear additive in motor oil, but there are others that are just as effective (but more expensive).  Adding "external" zddp to an existing lower zddp oil can work BUT if you add too much, the cleanliness/detergency additives can be compromised.  The Joe Biggs Racing racing oil has something like 3000ppm of zddp, but then it gets changed every 500 miles.  So, discretion can be the better part of valor in adding too much zddp for not a lot more "protection".  Joe Gibbs also has a specific motor oil for direct-injected gasoline motors, too.

 

When the issue of zddp levels and "replacement aftermarket camshafts" first arose, Comp Cams' recommendation was "either Rotella T or synthetic motor oil".  Rotella T for its obvious higher zddp (anti-wear) levels and synthetic oil for its tougher oil film (anti-wear) composition.  That told me that the aftermarket people probably put enough Parkerizing on their cams to get them by with the higher zddp levels, but not enough to get them by with the lower zddp levels.  I also suspected that each would have their own "oil additive" for their cams, which most had available within a few years.  THEN, some offered "an optional extra" of a thicker Parkerizing coating on their aftermarket cams!  To me, that verified my earlier suspicions of why things were happening as they tended to.

 

Hardened valve seats in a Buick Nailhead?  From what others who've done that have mentioned, probably not a good idea to put seats in a Buick Nahilead cylinder head until valve seat recession might require it.  The water passages in the head, near the valve seats, tend to be closer to the combustion chamber than on other GM engines, so it's easier to break through to the water passageway when doing the cutting to install the seats.  And that means finding another cylinder head, usually.

 

The particular higher-nickel metallurgy that Buick used in their engines and cylinder heads didn't really need to have "hard seats" or "induction hardened" valve seats prior to the early-1970s announcement that all GM engines would have hardened valve seats so their engines could run on unleaded fuel with no maintenance issues.  Chevys and others needed them, Buicks didn't.  But they had to comply anyway.

 

Enjoy!

NTX5467

  • Like 1

Share this post


Link to post
Share on other sites
5 hours ago, SpecialEducation said:

Weight of the oil is dictated by bearing clearances. Too thin and it will shear & it won't do the job. To thick and it can’t get into where it needs to be and it won’t do its  job. Heavy oil also puts more stress on the oil pump drive. 

 

The ONLY reason to go heavier is if the engine is significantly worn and you have low oil pressure. 

 

Additives are a completely different story. You need ZDDP (aka zinc phosphate) in the oil to keep from destroying the cam & lifters. 

 

Ignore everyone who cites a brand preference, and look at actual oil specifications. API SN spec won't cut it in these engines. CJ-4 spec (often marketed as diesel oil) will. If an oil meets both, that’s fine. CI-4 is ok, but not as good, CK-4 is insufficient. Beware of labels that cite “CJ-4 compatible.” That’s not the same as “equivalent.”

 

Or just buy an SN spec oil and add a ZDDP additive. 

 

For in depth info, start here:

 

http://www.widman.biz/English/Selection/Oil.html

 

I wouldn't claim that as a credible source. Reading through it, he cites facts and studies and information without citation, which is really poor for a research paper like this. Anyone can say "studies shown" but I'm personally interested in exactly what studies are shown. There's always room for bias, whether the author is correct. 

 

I'm anticipating someone in this thread to chime in and say using zinc in flat tappet engines is an urban myth with many thousands of miles on normal oil. 

  • Confused 1

Share this post


Link to post
Share on other sites
7 minutes ago, Beemon said:

 

I wouldn't claim that as a credible source. Reading through it, he cites facts and studies and information without citation, which is really poor for a research paper like this. Anyone can say "studies shown" but I'm personally interested in exactly what studies are shown. There's always room for bias, whether the author is correct. 

 

 

I’m not saying I agree with that paper 100%, but it is a good starting point, especially for this audience. 

 

I worked for years as a propulsion systems engineer, and I know things I can’t say out loud because I’m still loosely related to a major piston engine manufacturer (sister company).  While there are some differences in the way piston aircraft engines are designed, built, and operated, the basics of oil shear and the effects of additives is very much the same. 

 

The big difference is that the majority of cars are scrapped when they need a new engine, where an aircraft engine overhaul is scheduled maintenance. We tear down these engines at a high frequency and track a lot more data from the field, because things like a worn cam lobe can result in an airplane in the trees instead of in the sky. 

 

 

  • Like 1

Share this post


Link to post
Share on other sites
3 hours ago, Beemon said:

I'm anticipating someone in this thread to chime in and say using zinc in flat tappet engines is an urban myth with many thousands of miles on normal oil. 

But you already said it...

Talking nailheads:  I have never seen or heard of an oil related failure due to lack of zinc!  I checked the cam and lifters on my 55 322 at 80,000 miles; it now has 100,000 miles on the engine and will head out for a 3,000 mile trip in a few days (20w50 Castrol gtx).  Not only were the cam and lifters pristine, but the cylinders still showed hone marks.

  • Like 5
  • Thanks 1

Share this post


Link to post
Share on other sites

Willie doesn't watch much TV......just tears down his engine for fun.

Good to see you and Bill today.   I was a little disappointed by the small number of cars at a national meet.

Edited by Barney Eaton (see edit history)

Share this post


Link to post
Share on other sites

I suspect that zddp kind of made-up for the poorer film thickness of the "dino" motor oils of earlier times, in anti-wear issues.  With the more modern blendstocks AND synthetic formulation, zddp levels could well be safely decreased with no issues.  Remember, the original Comp Cams recommendation was "Rotella T or synthetic".  Rotella T, at that time, was a "dino" oil.  Diesel "dino" oil was either straight weight or 15W-40.  Synthetic 5W-40 diesel oil wasn't around back then, as it is now.  In much more current times, 10W-30 diesel synthetic oil has become available, as have "syn blends".

 

Back in the later 1960s when motor oil "super oils" (10W-50, for example, with their wide viscosity range from improved chemistry), there were also many oil additives on the market to help "normal" oils along a little bit.  This was also close to the height of the increased lift/longer duration/higher rpm capable/high horsepower V-8 engines.  STP was usually the most recognizable oil additive, used by many racers.  It was an oil thickener which was supposed to increase the oil film strength for higher-load situations . . . one of which could have been the higher loads at the cam lobe/lifter interface.  ONE of the competitors was named "STUD", with a tailed-devil graphic as its logo.  Reading the container, it had a long word starting with "z" (most probably zincdithiophosphate?) that talked about "high load" protection.  It was not until years later than I connected that additive with the cam lobe wear issues of the '80s.  That additive only lasted a few years, that I know of.  The reason for the "super oils" was the response to the bigger, more powerful, higher operating temp, engine operating conditions of that time.  It might well have been when zddp levels were increased?  Just that we didn't know about zddp per se back then, OR why it was needed?  And things have progressed from there!

 

NTX5467

Share this post


Link to post
Share on other sites

The manual states what viscosity and air temps of the region the engine will operate.  I use 10w-30 and sometimes 20W-50.   These I purchase from Lucas Oil(classic car). 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now