We have a Cat backhoe with 8 quart capacity, a Case trackloader with about 9 quart capacity, and a John Deere 550J dozer with 12 quart capacity. I believe they all specify a 500 hour OCI's. That seems way too long to me. Just for comparison we have a 07 Chevy Tahoe with about 1,000 hours on it and 47,000 miles or 23,500 miles every 500 hours. We use Shell Rotella 5-40 synthetic and oem filters in the heavy equipment. What do you think about 500 hour OCI's??