Well, the title may be overambitious, but I just got this 03 Corolla LE with over 233,000 km for uber and I'll like to make it the best it can be, man needs to eat. Been fixing minor stuff, but the major now is the engine. Owner is forming 'busy' to tell me the exact oil weight he used but I want to return it to manufacturer spec 5w30. But I suspect sludge build up already (oil cap has sludge under and engine cover has some seepage around it). Engine drives better after I put plugs closer to manufacturer spec but I feel vibration at 3rd gear now and more vibration at reverse). Also, I could see some oil signs around the plug when I took them aout after about 3weeks of usage for some reason, is that a seriously bad thing? Also, I had blue smoke after second oil change to 20w50 (ddnt know about oils then). But there was no smoking when I bought the car this Jan. Oil shorts now too. So my plan is to first change to full synthetic 5w30 mobile, see if smoking stops. If not, then look at gasket and oil seals (pls who has an idea of the price?). For the sludge I am hoping synthetic oil will help a lot, but I'm reading stuff about scraping oil pan and valve. Please any advice /assistance is appreciated, please I can't afford to loose an engine in this hard time, wey schl fees don reach sef. Thanks.

You want to kill an already dying engine. Safe your self the cash of doing synthetic since engine is already smoking. Check for external oil leaks. As for plugs get wet by oil. Replace valve cover seal. Does the blue smoke continuously comes out even on motion. You need to do a smoke test 101 to confirm this. Good luck

mayor2013:
You want to kill an already dying engine. Safe your self the cash of doing synthetic since engine is already smoking. Check for external oil leaks. As for plugs get wet by oil. Replace valve cover seal. Does the blue smoke continuously comes out even on motion. You need to do a smoke test 101 to confirm this. Good luck

I get that comment of killing a dying engine a lot but don't understand it. I smoke stops when engine is warm and in motion, does that mean it's just seals? Any idea of the cost of valve seals?