When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It could be that the 89' has a rear heater, those rear heaters could add some but not the amount your saying. I'm guessing that you probally are not fully draining the coolant on the 89' and thats why it's not taking as much make up coolant. I can't see that there would be that much difference in coolant capacities otherwise. Do both vehicles have the same size of radiator? that might account for the difference somewhat.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.