Malibu 2000 3100 motor Change the oil Change oil pump Motor still rattling

SOURCE: oil pressure

does the engine make any raddle noise when you start the engine. if not may just need oil presure sensor.

SOURCE: Nissan KA24E rattle at start up

ah the venerable napz motor extra coil extra plugs and a weak oiling system check oil filter bypass for coked stuck return spring...how many miles on motor? if crank bearings are failing no oil can get to top (warm metal things swell and make it less noticable)

SOURCE: 04 corolla. Oil light comes on. Full of oil.

the oil pump on any car is rarely the cause of low oil pressure. if you remove the oil pressure sending unit and install an oil pressure gauge,even the type you can buy as an add on,and the reading you get is low.the problem is genrally worn out main crankshaft bearings.to avoid unneseary replacement of these,you should buy some plasti-gauge from an auto part store remove the bearing caps one at a time and measure the clearance this way.there is a risk here because the smallest grain off dirt that getts into the bearing, crankshft will ruin the bearing when you restart it.if these are worn out you probabably shoul consider replacing the engine because the other bearings are probably also worn out by this time.

SOURCE: How often do you change the motor oil? The motor

Oil change recommended is every 3,000miles / 5000km for local short running around. If you clock up the miles quickly then extend the oil changes to 6,000miles /10,000km
Oil filter is every second oil change.
Use reputable multi grade oil 15W/40 or similar, Do not use standard SAE 30 single grade oil. You do not need to use synthetic / semi-synthetic oils either.

SOURCE: 2001 ford escape overheating

try replacing your radiator cap