Apparently this is big enough problem that they have an article about it:
http://www.gmtechlink.com/images/issues/arcv_pdf/12_00_e.pdf
Identifying OE Engine Oil Filters
If you question whether the proper routine maintenance has been performed on a vehicle, there are several things to look at.
One way to check if routine maintenance has been performed is to identify the current engine oil filter. If the vehicle still has the original equipment (OE) oil filter after 20,000 miles, for example, routine maintenance may not have been performed .
For 1998-2001 models equipped with a GM Powertrain produced engine, there are several ways you can distinguish between OE oil filters (factory installed) and non-OE oil filters (which have been installed after the vehicle was new).
This information applies to all vehicles except Saturns , Chevrolet Metro , Tracker and Prizm,
Cadillac Catera, and 3.5L V6 (LX5) engines
with the PV6 cart r i d g e type filter.
1. OE filters have a small part number label
(25.4mm x 35mm). Non-OE filters have a larger label (39mm x 60mm) that includes
tightening instructions.
2. OE filters have a seal with a red teflon
coating. Non-OE filters have a black, uncoated
seal .
3. All filters have an ink-stamped 6 digit Julian date code at the wrench flat end of the filter (065003 = March 5, 2000, 3rd shift). OE filters have an "OE" at the end of the date code. Non-OE filters do not. For Chevrolet Metro and Tracker models, the original filters have Suzuki printed on them, and replacement filters do not. On Chevrolet Prizm models, the original filters are black with white Japanese characters, and a caution in English. Replacement filters do not have any Japanese writing.
The next time routine maintenance comes into question, identifying the engine oil filter may help you determine if scheduled maintenance has been performed.
– Rich Burrell
http://www.gmtechlink.com/images/issues/arcv_pdf/12_00_e.pdf
Identifying OE Engine Oil Filters
If you question whether the proper routine maintenance has been performed on a vehicle, there are several things to look at.
One way to check if routine maintenance has been performed is to identify the current engine oil filter. If the vehicle still has the original equipment (OE) oil filter after 20,000 miles, for example, routine maintenance may not have been performed .
For 1998-2001 models equipped with a GM Powertrain produced engine, there are several ways you can distinguish between OE oil filters (factory installed) and non-OE oil filters (which have been installed after the vehicle was new).
This information applies to all vehicles except Saturns , Chevrolet Metro , Tracker and Prizm,
Cadillac Catera, and 3.5L V6 (LX5) engines
with the PV6 cart r i d g e type filter.
1. OE filters have a small part number label
(25.4mm x 35mm). Non-OE filters have a larger label (39mm x 60mm) that includes
tightening instructions.
2. OE filters have a seal with a red teflon
coating. Non-OE filters have a black, uncoated
seal .
3. All filters have an ink-stamped 6 digit Julian date code at the wrench flat end of the filter (065003 = March 5, 2000, 3rd shift). OE filters have an "OE" at the end of the date code. Non-OE filters do not. For Chevrolet Metro and Tracker models, the original filters have Suzuki printed on them, and replacement filters do not. On Chevrolet Prizm models, the original filters are black with white Japanese characters, and a caution in English. Replacement filters do not have any Japanese writing.
The next time routine maintenance comes into question, identifying the engine oil filter may help you determine if scheduled maintenance has been performed.
– Rich Burrell