I have a Clark Forklift (GCS25MB) with the one-speed automatic transmission (HR510) which does have a torque converter. I want to change the transmission oil and I want to be sure I use what is correct? The manual says to Use Amoco 300 SAE20. What would be a correct cross over from this? Thanks.
Correct Transmission oil for a Clark Forklift?
- Thread starter Rick7
- Start date
Amoco 300 was plain old motor oil, so straight weight 20 grade oil is what it calls for.
Straight 20 weight is getting hard to find so you could possibly use a ISO 68 anti wear hydraulic oil, but I'll defer to others for their expertise.
This little guide says SAE 30 oil for the 500 series trans -you gotta go way to the end where trans service is described.
https://www.clarkmhc.com/wp-content/uploads/2024/02/OM-520.pdf
https://www.clarkmhc.com/wp-content/uploads/2024/02/OM-520.pdf
"Do not substitute."
SuperTech off-highway SAE-30 weight diesel oil with the CF and SG rating is probably as close as you can get to the original spec and would work great.
Good eye! I love how the BITOG community pulls together for its members!
The C500 series uses dexron. The gc series used 30 wt HDEO rated engine oil can use HDEO and the later models used 2776236 which is a tractor hyd fluid. I worked 23 years at a Clarklift dealership and that is it .
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So you sold and serviced these with fluids other than what the manual calls for? The op has an HR 500 series not a C500...so that is why I posted the service manual info for his specific application stating to use motor oil and NOT to deviate.
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