98 F150 5.4L, i recently changed from 5w 30 to 5w30 synthetic. there is 106,000km on the engine. will it make a difference on the longjevity of the engine, or am i just throwing money down the toilet?

 

might just cause a leak... if you always used regular oil then switch to synthetic.. it will leak thru the seals so if an oil leak is the difference you want than yes it will make a difference

 

I switched to Mobil 1 on my wife's old car when it had 100,000 MILES on it. No leaks and this was on a POS Plymouth Acclaim with the 2.5l in it....

I then switched my truck to Mobil 1 with 85,000 MILES on it. No leaks to this day with around 165,000 on the clock now.

We don't have the Acclaim anymore, but it never leaked and it ended up with over 130,000 on it when it got traded in.

Does it help with longevity?? I don't know.... "motor oil is motor oil" as long as it meets the specs of your engine.

Do whatever makes you feel better.... As long as the oil meets the specs, then it should be fine. IMO, going to synthetic will not 'automatically' make your engine leak... If the detergent properties of the synthetic clear away some gunk plugging an ALREADY EXISISTING leak around a gasket, then that could cause a leak, but the leak was already there.... Just plugged up....

Call it however you like....

Mitch