Common transmissions in 1985 Chevy trucks included:
* TH350 (3-speed automatic): This typically used Dexron II transmission fluid. Dexron III is also often compatible but always check your owner's manual.
* TH400 (3-speed automatic): This also generally used Dexron II or possibly Dexron III. Again, consult your owner's manual.
* 700R4 (4-speed automatic): This transmission required Dexron III fluid.
* SM465 (4-speed manual): This used gear oil, often a SAE 80W-90. The specific type of gear oil might be specified in your owner's manual (some might call for specific additives).
* Other manual transmissions: Other manual transmissions might have used different gear oils.
To find the correct fluid:
1. Check your owner's manual: This is the best source of information. It will specify the correct fluid type for your truck's transmission.
2. Locate the transmission identification tag: This tag is usually located on the transmission case itself. It will have a code that identifies the transmission type. You can then use this code to look up the correct fluid online or at an auto parts store.
3. Check the dipstick (if applicable): Sometimes, the dipstick will indicate the recommended fluid type.
4. Consult an auto parts store: Bring your truck's VIN or the transmission identification information to an auto parts store. They can help you determine the correct fluid.
Do not use the wrong fluid. Using the incorrect fluid can severely damage your transmission.
