1999 QX4 engine oil, synthetic or regular 5W-30?

[akers912]

I daily drive a 1999 QX4 with almost 163,000 miles and i plan on doing an oil change very soon. I just got a purolator BOSS oil filter and i bought five quarts of Pennzoil platinum SAE 5W-30 full synthetic oil. Should I use this synthetic oil or should i use conventional oil? I've seen different threads saying yes and no so its really hard to decide!

[akers912]

My QX4 has 163,000 miles on it and i plan on doing an oil change soon. I have no idea what kind of oil has been previously put in it. should i use synthetic or regular 5W-30?

[ArmedAviator]

If you want to increase your oil change interval (7-10k), go with "synthetic". If you want to keep a lower (3-7k) OCI, go with regular.

[ArmedAviator]

Please see my post in your other thread.

[Rogue One]

Threads merged. akers912, please don't create multiple threads for the same topic.

[UpUp_Away]

Just use synthetic and don't look back. Synthetics don't create leaks, they just clean the sludge and buildup in your engine really well. The "leaks" stories come from the sludge clogging up the leaks that are already there, and switching to synthetic cleans up the sludge, which would unclog it (which is a problem you should fix anyway and not put off by using low grade oil).

If you're just switching to synthetic after a lifetime of conventional, I'd do my next oil change a bit sooner, say, 5k miles, because there is going to be a surge of sludge that is going to be eaten up by the oil and filter, after which you can keep your 7.5-10k oil change interval.

[barnaclebob]

Been using synthetic for only about 15k miles now with no issues, 5k change interval, 150k total.