Help. Oil dipstick shows oil low but oil is full.

[Miles.Manderson]

All help and comments is appreciated. I have a 1997 Lexus LX450. Engine is 4.2l petrol straight six. The oil light comes on and off and when I checked the dipstick and it shows that there is low oil but when I take off the engine oil cap to add more oil I was shocked to see that the oil is filled all the way up to the threads for the cap. I haven't added any oil since the last oil change so I know it has either the Forrest amount or slightly less due to Burling a small amount of oil. So there I don't know why it would be showing it filled all the way to the top. Possible clogged oil line stopping it from sitting in the oil pan? Any help will be appreciated thanks

[joaa]

There are oil return holes in the head that are probably plugged up with sludge