what is the correct oil filter number?

[James S.]

I need information on whitch oil filter number is correct for my '69 427/390 engine with a body tag dated for June 10. Is it the PF-25 or the PF-29?

[Joe L.]

Re: what is the correct oil filter number?

I need information on whitch oil filter number is correct for my '69 427/390 engine with a body tag dated for June 10. Is it the PF-25 or the PF-29?

James------

By June 10, 1969 I'm pretty confident that the PF-25 was in use. However, I don't know that we'll ever have certainty on this.

[Terry M.]

Re: what is the correct oil filter number?

PF 25. But there is a lot more to that oil filter than the AC Delco number. And questions about the rest of it will get you square into some real controversy. Let me offer something that is non-controversial. The oil filter you want is white and has some embossing on the bottom. After that you will find some of us "discussing" some details fiercely.

[Mark D.]

Re: what is the correct oil filter number?

Ah Lawdy, to type so much on an iPhone is such a cross to bear.

Great question so, I'll give you my opinion. Joe Lucia offers compelling evidence/research regarding oil filters of this time period. For example, due in large part to his research, it is now believed that the PF-29 was used on all MY 1968 Corvettes and up to approx. 13,000 VIN in MY 1969. After that, PF-25 is accepted as the assembly line oil filter. This PF-25 filter is generally accepted as being embossed on the bottom up to (IMO) sometime in MY 1970 when they were no longer embossed.

Now it gets interesting. Again, due to Joe's research, there is evidence that assembly line PF-25 filters were white with black markings. Those markings consisted of the AC logo along with Type PF-25 on one side of the logo and Full Flow on the other side. This is backed up by known original filters used on Camaros of the period along with another source that I will let ID themself.

My gut tells me assembly line filters were black and white whereas over the counter examples were 'more colorful.' Only time and more data points will tell. Terry Mac's 'Boy Scout' theory will make absolutes difficult. I would be willing to bet good money that assembly line filters, both PF-29 and PF 25 (embossed and otherwise) were black and white.

That's how I see it.

Mark

[Terry M.]

Re: what is the correct oil filter number?

And I am with Mark, however, we are a long ways from having enough evidence to put into a judging manual.

My "Boy Scout" theory is that all Corvette owners were good Boy Scouts and changed oil and air filters like it was a religion. Thus we have no surviving examples with original oil and air filters. Other GM models will have to produce OEM examples for us.

Now Jim -- ain't you glad you asked?