69 Big Block Oil Dipstick

[Chuck G.]

The judging manual calls for a dipstick with a white button. The manual also mentions that the longer, air conditioned dipsticks are often found on non-AC cars. Paragon sells the short, non-AC dipstick with the white button, but it does not have the part number stamped on it. When I bought my 69, it had the longer "air conditioned" dipstick with a RED button. This dipstick is stamped 3981088, which, according to my 1972 parts book, is the right number for 69-72 big blocks. It corresponds to the length listed in the parts book. Is this correct for my 69 427/400 no air car? How about the red, not white button? Is the white button only on the "shorter" non-AC dipstick, which, by the way, I cannot find listed in any of my parts books? Is the judging manual incorrect on this point? Any and all help will be appreciated. Thanks Chuck Gongloff

[Joe L.]

Re: 69 Big Block Oil Dipstick

Chuck-----

I don't believe that the 3981088 dipstick is original for your car. As far as I know, all 69 427s and early 1970 454s used the GM #3959158 dipstick. This is the dipstick with the white button. The 3981088, with the red button, came into PRODUCTION use in mid 1970 production. However, by early 1971, GM #3959158 had been discontinued and replaced in SERVICE by the 3981088 for all 69+ Corvette applications.

Check your dipstick end. Look to see what engine oil is recommended. For 1969 era engines, GM recommended "MS" quality engine oil. Usually, 69(and even 70 or 71 engines) would have this indicated on the dipstick end. If your dipstick has this inscription, it may or may not be original since early 3981088 SERVICE dipsticks would have had this, too. However, if yours has "USE SE" engine oil, or some other "modern-era" rating, it is certainly a replacement.

Incidentally, if there ever was a special dipstick for A/C-equipped cars, it was NEVER available as a SERVICE part. NO parts catalog that I have going back to 66 big blocks indicates any special dipstick available for A/C big blocks.

Another interesting point: The 3981088 dipstick was used only with dipstick tube GM #3981089. Any Corvette originally supplied with the 3981088 dipstick(mid-70+) would have also had the 3981089 dipstick tube. However, by early 1973, the 3981088 dipstick replaced all previous 65+ Corvette big block dipsticks. Consequently, if a 65 to mid 70 Corvette big block owner were to replace his dipstick with the post-73 GM service part, they also have to replace their dipstick tube with the 3981089 tube. Failure to do this will result in incorrect oil level readings. You'd be surprised at how many big block owners have scratched their heads trying to figure this one out.

[Chuck G.]

Re: 69 Big Block Oil Dipstick

Thank you again, Joe. I "fouled up" on one point. I was going by my recent judging sheets on the dipstick, and hadn't pulled my "repro" from the car to check it. I had a "deduct" for no part # on my Paragon dipstick. When I actually pulled my white button dipstick, there was a part number there, number 3925520. I guess that the judges missed it, and I didn't double check. That number does not correspond to the 3959158 number that you have. Both the white button Paragon repro and the red button replacement are stamped "use SE" oil. I can't find "MS" anywhere on either. The red button dipstick is fully 24 inches long, while the white button reproduction is 18 1/2 inches. I certainly can see how mixing and matching these dipsticks with the incorrect "tubes" would create havoc trying to get the right oil level reading. Thanks again for your help and advice. Chuck Gongloff

[Joe L.]

Re: 69 Big Block Oil Dipstick

Chuck-----

I believe that the 3925520 dipstick is the 67-68 part number. There were several different big block dipsticks used from 65 through mid 70. From mid-70 to end of production, there was just the one that ended up being the SERVICE replacement for all. The 3959158 was a production 69-only item. It was also available in service for a while, but was discontinued about 71 or 72. I will double-check the 3925520 number this evening for application.

[Wayne M.]

Re: BB Dipsticks

Chuck, Joe: Re long dipstick & tube for '69 A/C cars -- I don't have the technical manual, but I believe the longer set WAS used for A/C cars. Refer to the legendary "Wildest Corvette Test Yet" article of July '69. One of the cars was an L36, M20 with C60. A photo of the engine compartment clearly shows the long dipstick; you can tell (in addition to its height) by the vertical position of the handle, due to the curve in the upper tube. One look at the mess of hoses for the heater, freon, and A.I.R., and it becomes evident that checking the oil with the short tube would be a real knuckle-burner.

Chuck, let me list what's shown in the Jan '70 Corvette Parts Manual: Your #3925520 is given as a replacement for '65-'66, and as the current # for '67-'68 (all big blocks). The length from the tube seat to "full" is 17.41", and the "add" line is a further 1.09". As Joe has said, the #3959158 is called out for '69 (and '70 - at least to the catalogue date); but the "add" line is another 0.5" (total 1.59") from the "full" mark -- GM error ? BTW, the upper tube is #3870324, a (short) replacement for '65-'66, and the correct tube for '67-'70 (427,454), at least to the introduction of the longer set in mid-70(?)

This is all so complicated that it's a wonder there's not more mis-matches of upper tube and dipstick, with disastrous consequences if the short tube is used with the long stick, and you don't count the quarts.

We need someone to bring this all together (Joe ?) as a sort of "Oil Level Management 101" and publish in the Restorer for all to benefit.

[Bill Clupper]

Re: 69 Big Block Oil Dipstick

Chuck, '68 parts book lists '520 as '67-68 application. ''71 parts book lists same for 65-68 none beyond that point.

[Joe Peplinski]

Re: 69 Big Block Oil Dipstick

My early '69 400hp A/C car has an engine oil dipstick that has a long handle, but no colored button of any type. My car is unrestored, and by it's condition I suspect that this is the original dipstick. Can this be correct? Did the button fall off at some time or was there no button on the A/C BB dipstick? Where was the button? On the loop you put your finger thru to pull?

As is, mine appears to agree with the photo of a 400hp A/C engine compartment in the Vette Veiws 68-72 Fact Book. Also the dipstick reads properly and the markings on the end of the dipstick are as follows, reading from the tip toward the handle:

"Add | | Full ENGINE OIL E"

The last "E" is turned so it points upward, relative to the rest of the writing. There is no mention of oil type "SE" or otherwise. Thanks.

Joe Peplinski

[Joe L.]

Re: 69 Big Block Oil Dipstick

Joe----

I don't dispute the fact that big blocks with A/C may have had unique dipsticks. However, if they did, the part was never available in SERVICE. So, if you lost or otherwise became seperated from your dipstick, the only one you could get from GM would be the "standard" dipstick. Often, dipsticks have the GM part number on them; it's too bad that yours doesn't since I don't know of any other means of finding out what its part number was. Even though it was not available in SERVICE, the item would have had a part number.

The "button" was located on the end of the "loop" portion of the dipstick and served to close the end of the small tubing that the dipstick handle was made of. It may also have served as a part identification color code for engine assembly workers and to prevent the the possibility of anyone getting their finger cut on the sharp end of the loop handle.

Most original dipsticks that I have seen have the engine oil recommendation on them. My original 69 small block dipstick has the "MS" engine oil recommendation on it. I also have several new GM spare dipsticks that I have acquired over the years. Each of these has an engine oil recommendation code which differs depending on the time period that it was manufactured inasmuch as the ratings updated from time-to-time. I also have several big block dipsticks and each of them has an oil rating recommendation on them.

Incidentally, the "MS" rating that I am referring to was a rating in the precursor system to the API rating system of more recent times.

[Chuck G.]

Re: BB Dipsticks

Hello Wayne: Thanks for the info. I measured my "Paragon" repro white dipstick, stamped 3925520. As close as I can get it, it measures 17 3/8 to the full mark, measured from the crimp above the "thimble" which covers the dipstick tube. It measures 18 1/8 to the "add" mark. I think that I'll continue to use it and look for an "original". It certainly would make life easier to have the longer, AC model. This repro is tough enough to get out. You have to "finesse" it past the surge tank. Chuck Gongloff