C-3 Dipstick?

[D S.]

What dipstick is this? It is in a 1970 LS-5 but has the characteristics of a 1971 or 1972 dipstick since it has a red plug and round level indicators but other than ADD and FULL there are no other words or numbers, not even an M stamp.


Thanks,
Scott Sims
Texas Chapter

[Warren F.]

Re: C-3 Dipstick?

Looks just like the two dipsticks in my two '71's.

[D S.]

Re: C-3 Dipstick?

Thanks, Warren. I suspected it might be a 1971. I know that 1970 dipsticks had black plugs and hash marks for oil levels and 1972s have roundish oil level marks and the added words USE SE ENGINE OIL. Some have M stamps, some don't. I learned all that from this TDB.

[Joe L.]

Re: C-3 Dipstick?

Thanks, Warren. I suspected it might be a 1971. I know that 1970 dipsticks had black plugs and hash marks for oil levels and 1972s have roundish oil level marks and the added words USE SE ENGINE OIL. Some have M stamps, some don't. I learned all that from this TDB.

Scott-----


Which 1970 dipsticks? As I mentioned previously, there were 2 different dipsticks used for 1970 LS-5. The early one was the same as 1969. The later one was the same as 71-74.

[D S.]

Re: C-3 Dipstick?

Scott-----


Which 1970 dipsticks? As I mentioned previously, there were 2 different dipsticks used for 1970 LS-5. The early one was the same as 1969. The later one was the same as 71-74.

Which 1970 dipsticks? The one described in the 1970-1972 Corvette Judging Guide. The JG doesn't differentiate between an early 1970 and a late 1970
dipstick but would like to see that inserted in the next edition as well as the 1971 dipstick without the words USE SE ENGINE OIL.

[Joe L.]

Re: C-3 Dipstick?

Which 1970 dipsticks? The one described in the 1970-1972 Corvette Judging Guide. The JG doesn't differentiate between an early 1970 and a late 1970
dipstick but would like to see that inserted in the next edition as well as the 1971 dipstick without the words USE SE ENGINE OIL.

Scott-----


Nuances such as embossments on the blade may vary over the L70 to 74 period. However, the basic configuration and length of the dipsticks did not change over the period.

[D S.]

Re: C-3 Dipstick?

Thanks, Joe. I always look forward to and appreciate your replies and comments as well as all other members input here on the TDB.

[Tom L.]

Re: C-3 Dipstick?

I was inquiring about these dipsticks in an earlier thread, in particular about the different lengths noted in the JM. Would you mind measuring the overall length? In my iquiry Joe L. mentioned that there was only one length, "end-to-end, developed length of 22-5/8". Meanwhile I have contacted two other '71 LS-5 owners and theirs are longer. One of them sent pictures see below.

[D S.]

Re: C-3 Dipstick?

Lynn, thanks for the photo. My 1970 LS-5 original dipstick is the same length as the one in the photo. Tip to tip it is 27-3/8" long. Mine is an AC equipped car. A friend in Houston, Melissa Neiman, has a 1972 LS-5 with the longer original dipstick. Her Corvette is also AC equipped.

[Tom L.]

Re: C-3 Dipstick?

Thanks for the verification, perhaps Joe will add something. In addition to what I said before, one of the cars I mentioned with this longer stick is a NON-A/C car. I'm sure that will help confuse things!

[D S.]

Re: C-3 Dipstick?

Thanks for the verification, perhaps Joe will add something. In addition to what I said before, one of the cars I mentioned with this longer stick is a NON-A/C car. I'm sure that will help confuse things!

Uh-oh. It sure did. Blows the heck out of the 'longer dipsticks might have been for AC equipped Corvettes'. I think I recall in an earlier post that Joe said there was not a part number he could find for the longer dipstick and Joe is very up to speed on his information. Makes me wonder if the same part number was applied to both the longer and shorter dipsticks but had a suffix number or letter to denote the difference.

[Joe L.]

Re: C-3 Dipstick?

I was inquiring about these dipsticks in an earlier thread, in particular about the different lengths noted in the JM. Would you mind measuring the overall length? In my iquiry Joe L. mentioned that there was only one length, "end-to-end, developed length of 22-5/8". Meanwhile I have contacted two other '71 LS-5 owners and theirs are longer. One of them sent pictures see below.

Lynn------


I don't recall when I provided that specification, but if I did I was either talking about another dipstick or I was just incorrect. I have several GM #3981088 dipsticks and, measured from very end-to-very-end, they are all 27-7/16" long. However, measuring a dipstick this way is not the customary way to measure dipticks in "modern times". The important functional dimensions are the measurement from the seat to the "add" mark and from the seat to the "full" mark. GM says that the measurement from the seat to the "add" mark for the 3981088 dipstick should be 24". I measure 23-1/2" on the dipsticks I have. GM says the measurement from the seat to the "full" mark should be 23-13/64". I measure 22-9/16" on mine. However, the discrepancy might be the result of a difference in what GM considers the "seat" and what I consider the "seat".

[Tom L.]

Re: C-3 Dipstick?

Joe, no harm, no foul. My car came with a nasty looking, incorrectly reading aftermarket stick and I just want to be sure I only replace it once. The reason for my origional post a couple of weeks ago was triggered by the JM. It indicates that there are two different sticks, one longer one shorter (I can post the quote if you don't have the newest copy of the 70-72 JM, but somehow I doubt it ), but the vendors that sell repro's list it as 22 5/8" long.

If anyone has purchased one of these sticks, perhaps they could post a picture of theirs similar to the way the picture I posted was taken. Perhaps that will clear it up for myself and perhaps the JM at some point. Thanks!!

[Warren F.]

Re: C-3 Dipstick?

Lynn & Scott,

I just went and measured the "end to end" lengths of both my '71's dipsticks. They are 27 1/2 in length.

[D S.]

Re: C-3 Dipstick?

Lynn------


I don't recall when I provided that specification, but if I did I was either talking about another dipstick or I was just incorrect. I have several GM #3981088 dipsticks and, measured from very end-to-very-end, they are all 27-7/16" long. However, measuring a dipstick this way is not the customary way to measure dipticks in "modern times". The important functional dimensions are the measurement from the seat to the "add" mark and from the seat to the "full" mark. GM says that the measurement from the seat to the "add" mark for the 3981088 dipstick should be 24". I measure 23-1/2" on the dipsticks I have. GM says the measurement from the seat to the "full" mark should be 23-13/64". I measure 22-9/16" on mine. However, the discrepancy might be the result of a difference in what GM considers the "seat" and what I consider the "seat".

I'm going to help you with this one, Joe. From a post by Carr Campbell in March 2008 you responded in detail:

The external configuration of the Corvette oil pan did not change in any significant way over the 1965 to 1974 period. However, there were several dipsticks used over the period and 2 different dipstick tubes. The first tube, GM #3870324 was used from 1965 through E1970. This tube was used with the following dipsticks:

1965-E67----GM #3860316

L1967-1968---GM #3925520

1969-E70----GM #3959158.

Each of the above dipsticks superceded the previous for SERVICE. So, the 3925520 became the SERVICE dipstick for 1965-E67 applications and the 3959158 became the SERVICE dipstick for 65-68 applications. This indicates that GM considered each dipstick to be functionally equivalent to its predecessors.

The only difference between the dipsticks are differences in the measurement from the seat to the "add" and "full" marks.

These are as follows:

3860316= 17-13/32" to "full" mark----18-1/8" to "add" mark

3925520= 17-13/32" to "full" mark----18-1/2" to "add" mark

3959158= 17-13/32" to "full" mark----19" to "add" mark

Exactly why GM saw it necessary to change the placement of the "add" mark is not known to me. However, the fact that each dipstick became supercessive to the former strongly implies that the change was not due to an actual change in the configuration of the oil pan. Perhaps, they just found out that they had gotten the calibration wrong and corrected it (twice). Or, perhaps some changes in the internal baffling of the pans affected the "add" mark. Changes in internal baffling did occur about 1969 or 1970. However, there was no change that I know of between 1965 and 1968 while two different dipsticks were used over that period.

My OPINION of the relationship between dipsticks and "colored plastic buttons" is as follows:

GM #3860316= "salmon" button

GM #3925520= white button

GM #3959158= red, green or black; maybe any of these; I'm not sure

The L70-74 tube was GM #3981089. All L70-74 used this tube. It was used only in conjunction with dipstick GM #3981088. This dipstick and tube is SERVICE for 65-E70 Corvette PROVIDING that the tube and dipstick are used as a SET. One or the other CANNOT be used with any of the 65-E70 parts.

GM's "official" specs for this dipstick are:

GM #3981088= 23-13/64" to "full" mark and 24" to "add" mark

My empirically determined (i.e. measured) dimensions of a KNOWN GM #3981088 (that part number actually stamped on the dipstick blade) are as follows:

22-9/16" to "full" mark and 23-5/16" to "add" mark.

Why the difference? It may be that the GM specs are based on DEVELOPED LENGTH rather than FUNCTIONAL LENGTH. Remember that there are 2 "waves" in the upper part of the dipstick. If "flattened out" (which is what developed length is based on) the dipstick would be longer. Using developed length for a dipstick is asinine but that doesn't mean they didn't use it. If so, the earlier dipstick specs I mentioned might also be based on developed length which would mean that "as-measured" specs would be different. I do note that the difference between the "full" and "add" marks is about the same for both the official and "as-measured" dimensions for the 3981088.