I'm about to buy a '96 maxima with around 115k on the odo. The owner used 20w50 dino oil in the engine. His logic was that if you use an oil that was any thinner or if you use synthetic oil alot of the seals in the engine would start leaking. But I'm thinking that a 50 weight oil would damage the seals more than anything. I'm not gonna take any chances running a synthetic oil so I was thinking a high quality conventional like Castrol GTX would be fine. But what oil weight should I be looking at with the engine's history taken into consideration? Thanks in advance guys.


P.S. I live in Miami.

10W-30 if you're going with dino oil

5W-30 is Nissan original fill.

I use Castrol GTX 5W-30. My car only has 53,000 miles and change on it. I have been thinking about switching to synthetic but I have only been putting 5,000 miles or less on the vehicle for each of the past 3 years and can't justify it. I change the oil every 3,750 miles or less and will likely continue on the way I am going right now.

It is. In this case though, given southern Florida, a dino 10W-30 would be a better choice over a dino 5W-30. The 10W-30 will be more stable in the heat and the difference between 5W and 10W at his typical startup temnperatures is neglible.

The 30W is the same regardless so stability will be the same when the engine heats up. 10W will just give some extra protection during startup, but not much over a 5W.

Thanks for the replies fellas. Castrol GTX 10W-30 it is.

Or should i go with Mobil 1 SuperSyn??

It's not the same. Being a 30 wt. at temp isn't where the extra stability I'm talking about comes in. The spread between 5W and 10W when cold, and the different chemistry's used to achieve it are the reason why one oil is more shear stable than the other. Even though they both meet the requirement to be called a 30 wt oil at 100c, there are still differences in how the oil will behave at temp. over the drain interval.

Go with Mobil1 and a Nissan filter.

stick with Castrol 20W-50, 191k mi. and runs like new.

Go with the regular dino Castrol 10-30W. OEM oil filter.

If you're ****, go with Mobil 1 Synthetic, not the Mobil Supersyn...thinks the Supersyn is a mix of dino and syn. I used full synthetic once...but eh.

Living in the desert myself, I prefer 10-30, as I never see snow except for...well can't remember.

My 240K '95 Max still runs strong, no oil burning, one small leak..but eh...but do you expect? The leak is probably a qt every 3 months. Thinks I'm more worried about the tranny flipping out one of these days.

Mobil 1 Supersyn is their full synthetic.

Shoot if the seals leaking when you switch to synthetic after 100,000+ miles is a myth than I'm going with Mobil 1 SuperSyn all the way.

iwannabmw how likely is that engine to develop a leak by switching to a thinner synthetic?

If the previous owner did regular changes and the engine seems relatively clean, you shouldn't have any worries. If they didn't the odds of you developing leaks is greater but not guaranteed.

It's not necessarily the thinner synthetic that is the problem. It's the extra detergency of the synthtetic itself that cleans out any gunk left behind from dino that was run too long or too hot. A lot of times what happens when seals do leak, the gunk is getting cleaned out. After that is gone, the esters that are in the synthetic can slowly start to re-condition seals and the leak slows. I saw this in a car with 170k that I switched over. Seals started to weep but they never dripped and I never lost any oil over a 5k interval.

Heh, ur right of course...but

Wonder where I made up my previous statement from???

Maybe I was thinking of some other brand that blends oil.