Just bought a1990 toyota 5 door hatch, and drove it 100km to get home only to find large oil leak under car . oil is a little redish in colour, any thoughts on this problem because the car ran beutifly coming home.

Check your oil level.

Possible emissions problem. get the ecm scanned & go from there.

look on dip stick you should see cross hatched area with add oil or oil full mark.if you wipe oil dip stick with a clean paper towel and dip stick look dry no sign of oil add little oil at a time see if oil level reach add oil mark or the full mark.if oil is low. low oil light will turn on if bulb is blowed but if dip stick look dry oil level could be low,add little bit at a time dont over fill.

You probably blew a seal somewhere. I would try to pinpoint where the majority of the oil is coming from then replace that seal. A lot of times oil pan seals, drain plugs, rear main seals and valve cover seals can cause large oil leaks.

probly need new head or valvegasket-pop hood and inspec motor to trace oil leak always chec out auto before purchase-20 min is worthwhile

Double check the fuses under the hood.
If there is no problems there, you have to open the hatch trim by popping off the clips. Look for the connectors enure they are non corroded or loose.

Sounds like maybe the ECU had taken in some water. Is your ECM located behind the engine on the firewall? There are two large fuses located on the passenger side wheel well in the engine bay. They are two large (2" plastic covers) over them.

change your thermostat and engine mounts

Water is conensation from the air conditioning system. redish oil is most probably a antifreeze leak, does it look like a redish water? If so then its antifreeze toyota uses a pink/red long life anifreeze. most likley from a water pump which is right in that area

pull your truck on car ramps, get under it and take a rag and whip where you see any kind of fluid. watch to see where the fluid comes from. if its redish color its transmission fluid. it could be oil, you migh want to check that. make sure your oil filter is tight, no oil is leaking from that. check your plugs on your transmission and oil. it will be a bolt on both. make sure their tight! feel free to write back!