The red dipstick engines had extra oil nozzles to cool te pistons from underneath. This design flaw caused these engines to burn lots of oil. The green dipstick from I think '93+, are without those oil nozzles. Those have a more normal oil consumption and are much searched after. Originally they are Renault engines, but Volvo had Porsche redisign the pistons, heads, (turbo) inlet manifold and I believe the ignition. So they are a lot different than the original Renault engine. Volvo also worked together with Lotus. Lotus designed the chassis for the 480, that's why those little beauties are like glued to the road!