Understand 'M' in engine numbers designate they were mfg at the Lansing plant. 1970s: W30s - W31s - any other?

 

The M in the VIN across a wide range of years indicates a Lansing build, no matter what model or engine. Starting in 1972 through 1974 at least, an M before the build year digit, “M2M” or “M3M” for example, indicated a 350 4 barrel dual exhaust. So until 1972, the M in the VIN had nothing to do with the engine code, just Lansing assembly.
Terry

 

Just to clarify, after 1972 the first letter code you would see in a VIN is in the fifth position (1972, M = 350 4 bbl, dual exhaust) and was an engine code. Prior to that, the first letter code would be in the seventh position. In any case the letter (or number for foreign-built cars) code in the seventh position signifies assembly plant (M = Lansing).

Hope this helps.

 

Just to clarify, lots of models besides the W cars were built in Lansing. If someone is claiming a car is a W car due to it being built in Lansing that's not accurate.

 

👍

 

And all W-Machines were built in Lansing, so anyone claiming a W-Machine without an M engine is not accurate.

 

Since a 442 is a W-machine (as in 29), that is not completely true in the widest interpretation of the word. However, all W-30,31,32,45, and 46 were made at Lansing and would have Lansing engines.

 

Let's take a step backwards. For 1965-1981 Oldsmobiles, the seventh character in the VIN is the assembly plant code. It has nothing to do with the engine. The letter "M" in that position simply means the car was built at the Lansing, MI plant. While all W30 and W31 cars were built at Lansing, that is an infinitesimal fraction of the total number of cars built at Lansing. Having the "M" in the VIN is necessary but not sufficient for the car to be a W30 or W31.

Starting with the 1972 model year through the 1981 model year, Oldsmobile used the fifth character of the VIN to designate the factory-installed engine. The character used and the engine it represented varied with the model year. For the 1972 model year ONLY, the letter "X" in the fifth position of the VIN indicated the L77 motor, which was used in the W30 cars (as well as in about half a dozen Cutlass Supremes that were turned into Hurst/Oldsmobiles that year).

 

1970 W32s could be built at any assembly plant that built Cutlass Supremes and 442s. 1969 W32s were only built at Lansing Assembly

 

Oh right, I forgot the SX had a W code.