150k, but some new seals -- Switch to synthetic oil now?

[Jesda]

This Q has 154,000 miles and had regular 10w30 its entire life, changed every 3k by the dealer with a Nissan filter. It also had valve covers done at 138k and a rear main seal not long ago. Should I go ahead and switch to synthetic oil? I'm thinking that I wont risk developing any leaks because the common leaky items have already been taken care of.

[rsiwicki]

My car had similiar history with oil changes always done at the dealer every 3~4,000 miles. I switched to synthetics around 140,000 and have no leaks or noticeable problems and now have 164,000 on the car.

[maxnix]

I'd say you are safe. Might consider a crankcase flush because I assure you there is some sludge in bottom of oil pan. If you do, add a can of MOA or have an extra .5 Qt. of oil on hand.

[Aus94Q45]

Lots of other places to leak beyond the valve covers and main seal. I would stick with 3K dyno oils changes and maybe upgrade to the Mobil 1 filter. If you change it at such short intervals I think that you will do just fine over time. We switched to synth on my wife's Landcruiser and the friggin oil pan (upper and lower) started leaking. I am sorry that I did it.

[Q45tech]

The problems of synthetic oil leaks occurred 15 years ago [still in peoples minds] when they didn't include additives to swell seals like conventionals do/did.

Most seals, valve covers have a 100k [or less life] without regard to oil type.

[heywier427]

has any one switched to synthetic and left the undergaurd off? that will catch any leaky oil and mask the leak if there is one. something to think about.

[texasoil]

I left the underbelly pan of fmy spouses car for a few weeks checking for any leaks( none), put it back.

Most 'synthetic' PCMO's today use severely hydro-treated/hydro-isomerized petroleum base oil and not the 'poly-alpha-olefin' that Mobil-1 uses. The two types of molecules are essentilly identical as far as engine oil service is concerned. Additive solubility in the 'dino-based stuff' is a little better. Heat stability,etc is the same. Cost is lots lower than for PAO stuff.

[DrewQ45]

has any one switched to synthetic and left the undergaurd off? that will catch any leaky oil and mask the leak if there is one. something to think about.

If it's not enough to drip past the shield then it's negligible.

[elwesso]

Tech is right... the oil leaking due to synthetic is in the past... its something that people like to blame on because HEAVEN FORBID they did not maintain their car and replace seals!!!!

Bottom line is that synthetics arent going to cause your engine to leak, however because you EXPECT it to cause leaks you may NOTICE them...

Heres the thign I have with synthetics- unless you've used them for a long time, i dont really see the point in starting at 150k. I use synthetic in my Q because its still under 100k and it has used synthetic non stop for the last few years... I am going to run dyno in the next fill for about 2 months (probably the first time this engine has seen dyno oil since its been in the US) and then change it out for something synthetic....

Im normally not really a believer in synthetics, but I especailly like the 0w40 in the winter time because its so easy on the engine... plus (maybe im wrong) it seems to me like it stays fresher longer. My driving cycle is all highway driving, but often the car sits for a few weeks at a time.... I have driven about 4,000 miles in the last 5 months or so, but id say 95% of that driving has been in a total of about 20 days and the rest of the time the car has sat.... Maybe im completely off base, but the M1 0w40 that I have in there that i changed in november still looks decent (its ready to be changed by my standards) even after the rough winter life..

so i guess my recommendation to jesda would be just to stick with a good oil like valvoline durablend or castrol GTX....

[qship96]

at 150,000 miles,switching to synthetic oil is a waste of money,as all the wear that could have been prevented has already occured!

[maxnix]

at 150,000 miles,switching to synthetic oil is a waste of money,as all the wear that could have been prevented has already occured!

Not so sure if you run it hard up to redline frequently, or in high heat or bitter cold.

Love they way mine run, and no deposits.