Packard Forum Index » V-8 (1955-56)

Thanks, Bobby. The thing about adding an extra quart is a known issue. There was a design failure with the oil pump. For that reason, tappet is an issue. The oil pump could be replaced with an Olds pump as I recall, but I remember seeing a number of posts on the topic with people saying just add a quart. It turned out that adding a quart did the trick.

My oil is thin. I don't know my oils in terms of what the numbers mean. But I think I heard 5W is thinner than 10W is thinner than 20W. Maybe I need to go to 20W next oil change.

Do I understand the numbers right?

5w is too thin for these engines. The FSM and Owner's Manual specifies 20wt. The '56 Owner's Manual specifies 10-30wt. as multi-weight oil came in about that time. I've heard that worn engines will actually do better with 30wt. I'm currently running 10-30 in my '55 as well as my '51 with no problems/noise. Don't make yourself crazy trying to find 20wt. I haven't been able to find it anywhere.

Jeff, there are two numbers that indicate viscosity (or 'thickness'). The first number refers to cold weather thickness (or 'flowability')...the lower the number, the easier it flows at colder temps. So, a 5w would be thinner/flow better at lower temps than a 10w..lower numbers provide better protection in colder climates, but less in warmer. The second number refers to how thick (or 'flowabile') the oil is at higher temps. So, a 50w retains it's thickness more at higher temps than a 40w, etc, so the higher the number at higher temps provides higher protection as it thins less. Typically, today's modern oils are blends of lower viscosity oils that flow better at (cold)start up and in colder temps, as well as higher viscosity oils that retain their thickness at higher temps. Now, there are 'Multi weight' oils like 5w-30, 10w-40, etc., which cover a range of temps providing maximum oil protection across the spectrum of operating (and ambient/outside) temps.

Today's modern engines are specifically designed to use a certain weight of oil. Our Packards were designed to operate with the then available range of single grade oils, and the decision was based more on typical outside temps., with a good compromise being something like a straight 30w in the summer and maybe a 20w in the winter. I wouldn't recommend a straight single weight oil as the range of protection is far less than a multi weight, and if you've actually got straight 5w in there, (which I'd doubt),or even a 5w-20... Id recommend you change it immediately, as it's too thin for summer (esp. in Texas!), and it can only make that clacking worse.

We don't have to make such decisions now, b/c of multi weight oils..and frankly, today's oils really are like rocket fuel compared to the brew available back then. As I've said, I use Rotella T 15w-40 and find it quite acceptable, it's a bit higher in detergency, a good thing since my engine's never been apart and I'm still running original rings which allow some blow by, and the 15w-40 is good for my summer only use (although it's really a great all season choice, too). If you find that the clacking is still occurring, you can try a 20w-50, perhaps the thickness might slow the leak down from the offending tappet...again, I'm not so sure about over filling to boost oil pressure, if this is a common issue with '55's, it might be worth while to address the cause with a new pump rather than adding an extra quart which could conceivably cause other problems.

There's a great oil site, bobistheoilguy.com really interesting info from guys (like me) that are really into motor oil.

Quote:

Bobby,

Good summary on oil viscosity.

Over filling the crankcase with an extra quart of oil is to raise the oil level to prevent sucking air into the system, not to increase oil pressure. Apparently, those who have done this have not experienced any problems with the higher oil level. I have not needed to do this and have no direct experience with this 'fix'.

I also agree with you that the 'repair' would be a new oil pump, rather than trying to 'fix' the noisy lifter problem by other means.

Thanks.

(o[]o)

No, as previously explained, you don't have water in the oil.

Maybe, you're using oil of lower viscosity. The 0W-30 is thin, thin, thin; 5W-30 only slightly less so.

Yes, on an engine which had not had a precision rebuild 15W-40 is the preferred summertime oil. As long as the temperature is above 40 degrees it will be fine.

If the engine is rebuilt to specs, 10W-30 or 10W-40 should be fine.

jack vines

I am pretty sure at this point I must have a 5W in there. I will go to 15W since it might tend to resolved the propensity for tappet better with less need to overfill as much.