5w30 or 40 for VQ engine?

[mac9128]

Hello. So trying to help out both my parents who have G35's with the VQ engines if I'm not mistaken. I talked to my father but hes kindof set in what hes doing. Now he normally goes it Valvoline and gets synpower 5w-30 then runs it 7-9,000 miles before changing it. I'm wondering it switching up to a 40wt might help protect their engines better? Or if it'd be a better option for him to go to jiffylube and get 5w-40 pennzoil ultra instead? I know GC is a great option but like i said its basically down to these two choice. The cars will likely be in the family for awhile so I'd like to help keep them running well as I might get one of them one day

thanks

 

[Lethal1ty17]

change it for him with 5w40 and tell him its 5w30. those VQ engines shear oil down a grade.

 

[dmiko]

If he doesn't race, I'd stay with 5w30. One thing I wouldn't do is go 9,000 miles with Synpower. Synpower is not known to be good for extended OCIs.
You didn't specify the year of the G35. The VQ35DE (2003-2006) is known to be hard on oil, less so VQ35HR (2007-2008).
In my 2004 G35, I used Synpower 10w30 last fill and had QS Q-Horsepower 5w30 and PP 5w30 as well as Shell Rotella T Syn 5w40 (RTS) before. I do some full throttle and don't hesitate to use Xw30, even here in California. But in severe service, I'd shorten OCI rather than use Xw40. Unless you drive really hard, then it might make sense.
5w40 made my engine a little smoother. But UOAs on this engine showed good results with RTS, Q-Horsepower 5w30, PP 5w30, Castrol Edge 5w30: http://www.my350z.com/forum/engine-and-drivetrain/258663-vq-oil-analysis-and-info-53.html

 

[TJPark01]

You're splitting hairs. 7-9k miles should be easy for Synpower 5w-30. What does the manual recommend?

 

[aquariuscsm]

From what I`ve read about VQ`s,go with the 40 wt.

 

[mac9128]

Don't know what the manual recommends, I assume 5w-30 and am pretty sure of it. I keep telling him not to push it that far but he drive a lot for work, all over new england and new york so a lot of them are highway miles but still, the earliest he'll change it is 7k because in his words "you can go a lot longer on these new synthetics, i want to get my money's worth" I've tried to talk to him but like I said, stuck in his ways. I doubt its not going to be the death of the engine just would like to keep it running well. That being said I've read the engines run better on thicker oil thus why I asked about the 5w-40. Mothers car is an 05-06 model fathers is 07-08 (the one that sees more highway miles) but she often forgets to change her oil too until I visit and tell her to which can reach 8-9k.

 

[SLCraig]

I used to run GC in my VQ35 back in the day.
I also ran M1HM 10w30.

(Both good results)

I noticed running standard 5w30's, near the end of the OCI the oil pressure light would stay on for quite a while near the end of the interval. (oil thinned out)

I definitely recommend as thick as possible in the 30-40 range.

 

[raytseng]

Originally Posted By: mac9128
Or if it'd be a better option for him to go to jiffylube


Your thought there reminds me of a guy who is worried about his stubbed toe, even though his arm is cut off.

To keep the car in best shape, I'd recommend the best use of your time is to search around for a local mechanic that can do the maintenance properly and for a fair price. Search yelp or cartalk or other sources.
Then send your parents there with whatever synthetic oil you want. I think whatever is in the manual is fine.

You can probably find a good place that will do it for less than $20labor+parts or you supply the parts. This would be cheaper than jiffylube where you are paying for convenience.

Who cares about the minuscule difference between 30w or 40w if you end up with stripped drain plugs, your fluids topped off with wrong stuff and anything else a bad oil jockey will do; let alone problems with more major service.

Chances are that even after 10years, no matter if you went with 30 or 40, you're not going to have any oil-related differences that can't be solved within 2 oil changes and getting all the oil changed out

 

[RumbleG]

I run Q Horsepower 5w-30 in my G sedan. OCI is 8K and I have been fine with this. 56K miles on my G.

Next oil change I am going to try Castrol Syntec with Edge. Just for a change.

 

[addyguy]

You're dad is a lot smarter than you give him credit for.

Any modern syn should do a minimum of 10k, especially with highway driving. His 7-9k regime is just perfect, and his engine will last as long as he wants it to.

If he's comfortable with that regime, just leave him to it - at least he is changing the oil, instead of just sying he is to busy to!