: So I've been using 5W30...

06-10-06, 02:50 PM
Without knowing it until my last oil change...and this time the mechanic put in 5W30 also (I think). I know 5W30 is better for cold weather but I've been using it in the summer too, but it doesn't get too hot up here in Wisconsin. Am I paying any future penalties for using 5W30 all the time?

06-10-06, 04:29 PM
5W-30 is the recommended oil for N* engines, year-round. Unless you have a block heater, you might be able to use 5W-20 in the winter for quicker oiling at cold start. Curiously, Ford and a couple of others now recommend 5W-20, even in their truck series. BUT, GM does not. If you want real peacxe of mind, go to a name-brand 100% synthetic and WIX filters.

06-10-06, 06:23 PM
my 96DeVille says it likes 10W30

if i were you i would do a search on oil - oil consumption - api grades

lots and lots been said around here on the oil thang

06-10-06, 11:31 PM
I know my 4.0 rora is 10w-30 and some had that on the oil filler caps as well. I dont even use 5w30 in the winter.

06-11-06, 12:03 AM
For the 1998 Deville, it's 10w30. You can do a search for it... forgot the technical discussion on it, but basically... short term like for winter use is ok, but not for all season long.

06-11-06, 12:36 AM
MY Northstart takes 10w-30, but I think its too thin for it, when it need a quart of oil added, I still get the "Check Oil Level" message even AFTER adding one quart. I have to put in 10w-40.

06-12-06, 01:25 AM
Yeah on my oil cap it says 10W30 clearly, but I forgot what the mechanic said about using 5W30 but pretty much he said don't worry about it.


El Dobro
06-12-06, 01:14 PM
1999-down uses 10W30, 2000-up uses 5W30. It was changed when GM started putting roller lifters in the 2000+ N*.

06-12-06, 04:25 PM
Thanks.....that explains the 5W-30 fill cap on my '02 N*.....it must have roller cam followers.

06-12-06, 09:33 PM
Thanks.....that explains the 5W-30 fill cap on my '02 N*.....it must have roller cam followers.
It does. The roller followers simply allow the use of 5W30 and that satisfies the EPA by "reducing resistance" and thus "improving" milage, but I doubt you could tell the difference without some pretty sofisticated instrumentation. I still use 10W30 in mine.

06-12-06, 11:37 PM
2000+ Deville manual show "5w-30 Preferred" throughout all temperature ranges while 10w-30 is shown for above zero applications but not labeled preferred.

My 98's shows 5w-30 for temperatures under 60 degrees (and below zero use) and ""10w-30 preferred" except for temperatures below zero.

Sounds almost the same to me.

In the simplest of terms the "-30" is basically the oil "lubrication" and the 10w or 5w is how much "effort" it takes to be to the 30. I think that’s how it is.

Really one doesn't need the 5w if in a warm area constantly since the oil is always ready to be go and never thick while other places it may get cold.

Now some real cheap brands of oil on the other hand break down easy if the are used outside the Cadillac book recommendation, so they slap that in to try and hopefully "funnel" the purchaser to something that will be suitable as be multipurpose for their vehicle. If buying a quality oil then I suppose they will give you the protection you want.

I currently have 5w-30 Kendall synthetic blend and have really liked the protection it gives so far, the car has seemed great since switching from whatever Napa has in their bottles to the synthetic blend of Kendall, the guy at the shop said I really don't have to run 10w-30 in the summer but he'll put it in if I want. Debating to use the High Mileage Kendall w/seal max. I like anything with seal in it since it would be nice to give a little extra help to those headgaskets on both sides of the gasket :)

06-13-06, 12:58 AM
Ranger, is it ok for me to use 10w-40?

06-13-06, 09:05 PM
I see no reason to, but I would not think it will hurt anything.

06-16-06, 08:56 PM
As I was told by "The One Whose Name We Dare Not Speak", flat-tappet Northstars are better off on 10w-30 unless it's obscenely cold. In Buffalo and Wisconsin, that could happen. I would not advise running 5w-20 in anything that it is not recommended for. That said, the 5w-20 blends and syns are pretty shear-stable and hold their viscosity whereas most 5w-30 dino oils are effectively functioning as a 20 anyway after about 2000 miles. But I still wouldn't use it in a N*.

06-16-06, 10:36 PM
If you have 50 or 100 hours you can find out more about oil than you ever thought possible here ... http://theoildrop.server101.com/cgi/ultimatebb.cgi

Go back to the 10w30 although you may be OK if it is synthetic?

06-17-06, 11:20 AM
Hi,in The Uk Where I Own A 1998 Seville Sts,it Says On My Oil Cap 10-30 Oil,but U Cannot Get That In The Uk,only 15-30 Or 5-30,would It Be Ok To Use Mobil 1 5-30w In My Caddy...kev

06-17-06, 05:28 PM
^if you can;t get 10w-30 then 5w-30 will do just fine.