I've been using their 10w-30 for a year or two now. You seem to hear a little more valvetrain noise from the engine. But, it did improve mileage. HP increase was only 5hp so, that could have been any number of factors. One of the chain stores had it on sale for 6 bucks a qt a few weeks ago so I bought a bunch.

 

I like to run 10-40 in the summer. Based off of no scientific analysis.. Turbo makes alot of heat, its hot outside, and the engine is going to be running hotter because of it. I run 5-30 in the winter.

 

Your car has a thermostat and a cooling system. It runs at the same temperature, year round, except on start up. The only difference is that in the summer, it starts at a higher temp and warms up faster, which is better for your engine, and makes your oil perform better. Using different oils in different seasons is utterly pointless.

 

My '91 gets different oil in the winter time and it's pretty clear it starts easier and warms up faster.

There is a big difference between -20F and 95F, worth it to use different oils.

 

once it's at temperature. Unless of course your engine magically stores thermal energy when it sits over night in the dead of winter.

Same goes with driving the car really hard on the highway, entering the city on a 90 degree day and sitting in traffic. The cooling fan can only remove so much heat from the heat exchanger.

I guess your statement is more applicable to summer useage because the car is designed to regulate the engines temp.. But still I'd prefer oil which can handle more heat without losing visocity.

 

I don't know if things have changed much, but back when the turbos first came out we use to use 20-w50 in them and had alot of turbo coking. Granted back then the turbos were not water cooled either. But we were told that the viscosity additives were whar was causing the coking in the turbo bearings. When we switched back to using 10-W30 the coking problem went away. I personally feel the lighter multi viscosity oils such as 0-W40 that ia recomended is the best to use, light oil for starting gets the bearings lubed quicker and the heavy viscosity for the hot hard driving. This is my 2 cents.

 

I think I'm going to start getting Rotella T synthectic 5w-40 at Wally World and use that year-round.

 

I'll probably jump on that with you, I was a mobil 1 0w-40 guy for a long time but might as well try something new!

 

So it sounds like the 20 might be to thick for start up. I'm ok sticking with Castrol 5W50.... it's on sale this week anyway.

 

I used to run 20w-50 in my aero. It was a bit thicker than my liking on startup. I switched to 15w-40 and things were a bit better, but now that I know where to get 5w-40 synthetic Rotella I'm just going to go with that.

 

well oil viscosity changes by temperature. Thats why the best way to determine if the oil is working is to use a oil pressure gage. 5 is probably on the low side for summer.

 

You know that the '5' denotes that, at 0 degrees F it behaves like a 5 weight would.

At startup on a 70F day, it is still going to be thicker than a 40 weight (as measured at operating temp).

 

Yes, it does change by temperature. That's why you buy multigrade oils like 5w40 that work well at all temperatures.

A 5wXX oil will be better for a SAAB at startup, regardless of ambient temperature. It just means that the oil will start out farther up the "temp vs. viscosity graph" than it would if it were colder outside. That's why you use it year round, and stop trying to out-engineer the makers of your car who devote their whole lives to studying and designing oil and engines and choosing the proper kind for your engine.

A 5w40 oil behaves THE SAME as a 15w40 oil at operating temperature. They used to preach "viscosity extenders reduce heat resistance" but synthetic oil technology has advanced beyond that.

 

Yes, it does change by temperature. That's why you buy multigrade oils like 5w40 that work well at all temperatures.

A 5wXX oil will be better for a SAAB at startup, regardless of ambient temperature. It just means that the oil will start out farther up the "temp vs. viscosity graph" than it would if it were colder outside. That's why you use it year round, and stop trying to out-engineer the makers of your car who devote their whole lives to studying and designing oil and engines and choosing the proper kind for your engine.

A 5w40 oil behaves THE SAME as a 15w40 oil at operating temperature. They used to preach "viscosity extenders reduce heat resistance" but synthetic oil technology has advanced beyond that.

I suggest you might want to look at buying an oil pressure gage. I see a huge difference in oil pressure from the winter to the summer and I am talking about when the car is fully warmed up. There is much more heat in the summer and my oil pressure drops down with rp 10w30 to where its marginal at best in 80F and up ambient temps. I have to switch to at least a 10w40 and will probably go back to a 20w50 for racing in the summer months.

Try opening you're hood in the hot summer months after beating on the car, it will cook you from 10' away

John

 

I think if you can't find the correct forum to post in about your Vig, you shouldn't be changing your own oil.

 

Shit. Thanks for pointing this out. It is should be moved away from this weak sauce 'NEW 9-3' forum anyway.

 

I use RP 10w40

 

once the new motor is broken in, rp10w40 is what my ng will be getting

 

Since the Viggen no longer sees winters I have been using RP 10W40. Its getting some fresh bottles today in fact

 

I don't know if anyone else has used it yet but try ELF Excellium Full-Tech 0w30. After a 10,000 mile run it tested better than the mobil1 0w40. and the insoluables(sludge producers) were only half that of the mobil.

 

I have heard very good stuff about the Eld Excellium line... Unfortunetly I have yet to see it on the shelf of any stores around me....

 

Some guy with an n/a c900 posted up an oil analysis for Mobil 1 0W40 on SC showing good results after 20,000 miles. Yes, 20,000 mile oil change.

 

Doesn't Saab recommend 0w oil?

 

yea its great stuff but i buy it by the case online at tekoil.
SAAB actually requires 0w30 not 40 in our manuals, but 40 wt shouldnt hurt anything besides hp(maybe 5 if your lucky) and mileage.

jack: unfortunately n/a and turbo oil abuse is no comparison whatsoever.

 

jack: unfortunately n/a and turbo oil abuse is no comparison whatsoever.

I just thought that was interesting. Also, the newer H blocks (234, 235, all those) seem to need higher viscosity to maintain pressure, c900s are not picky at all.

 

From what people are reporting, 30 weight oil in summer time is not providing enough oil pressure. 40 and 50 seem to be good for summer is what is my understanding.

I ended up putting in 5W50 Castrol in last weekend and she loves it.

 

Ice I run 0w40 in the winter and 15w50 in the summer (both mobil 1). Anybody that says it doesn't matter what oil you run probably has never had an oil pressure gauge hooked up to see the values as they change in regard to outside ambient temp.

I know that in my car an 0w-40 as outside temps approach 60 or higher continues to drop from ~40 psi at 2000 rpm to ~30psi at 2000 rpm. The higher the outside temp the more it drops. Idle becomes really scary to think about. With my 15w-50 I see ~40psi at 2k no matter what. There is a reason that saab, at least for the b2x4 series motors, included in the manual different viscosity grades for ambient outside temperatures. It was so that owners would have the proper oil pressure at 2000 rpm as stated in the WIS system that techs have access to.

Now the one thing I don't have is oil temp by oil grade in relation to the change in outside ambient temp cross referenced to oil pressure. Maybe I'll have that for you all one day.

 

No oil pressure data here, don't need it, c900t's can go forever on mineral oil, it's a non-issue.