its much more likely to be transmission fluid in his radiator, the trans fluid cooler is in the lower radiator,
and if its got a pin hole leak it can get there as trans fluid pressure is higher than radiator pressure,
if it had a coolant to engine oil leak, its much more likely he would have coolant in the engine oil,
unless he has a coolant too oil cooler installed,
as coolant pressure is at times high enough to push past head gaskets,
if not properly sealed or if detonation or corrosion has happened.
check both the engine and trans for fluid contamination, if you suspect the radiator take it too a radiator shop to be cleaned and tested.
my 1985 corvette came with a factory oil cooler, that runs engine coolant through separate but contacting internal passages, this warms the oil faster getting it flowing but tends to reduce the heat engine oil can reach as it absorbs oil heat effectively transferring it too the engine coolant on the car, where its transferred too air flow through the radiator, this does a decent job if your cruising but not on a high performance application where a larger transmission fluid cooler does a significantly better job
obviously this cooler mounts between the block and oil filter and runs coolant through separate passages with a common wall to the oil flow so the coolant which is generally 10F-20F cooler than the oil will absorb some of the oils heat load. (use of the extra long oil filter,
BTW I DON,T KNOW WHO SELLS THESE BUT IVE GOT TWO ON MY CORVETTES OIL FILTERS AND THEY EASILY REDUCE OIL TEMPS 7-15 DEGREES
I don,t know where they sell these, finned aluminum filter covers now ,a few years back these were $20 each and significantly longer that this picture shows,
in fact they were the length of the long oil filter ,and believe it or not the combo of the longer oil filter and finned cover dropped my oil temps an additional 5 deg F , EASY TO PROVE by simply removing and replacing the slip on finned cover several times after keeping detailed records while cruising the interstate at a steady 70 mph (not a big difference but for $20 well worth it!
and a larger capacity baffled oil pan, also helps as it exposes more surface area to cooler under the car air flow)
http://garage.grumpysperformance.co...fo-and-derale-trans-cool-pans.662/#post-12989
Last edited: 4 minutes ago