auto_editor

Say you have a 307 that just passed its 170k-mile birthday without ever having been "touched" beyond maintenance.

It's still game for whatever trip you might want to use it for, but it's clearly on pre-financial-crisis-style "borrowed" time.

Everything official lists 5W30 as the oil grade to use, and it seems to work fine until the engine gets fully "hot", after which the "OIL/CHOKE" light first flickers--then stays on--mostly when in-gear at a stop.

[The low-pressure-warning really only comes on at a stop or barely-rolling (backing into the driveway, for instance), and usually goes away if I put her in Neutral when stopped, once rolling above 5 mph, once "cooled" via slow driving for a time, etc. Some of THAT I've been told might be transmission-related, but that's ANOTHER problem, not THE problem... ]

I've been told to move "up" with the oil so that the pressure won't drop far enough to light the light, but others warn that a higher-temp oil won't properly lubricate at start-up the way 5W30 can. So, for the purposes of SUMMER driving (I live in SE Michigan, so snow's an issue at times) what, if any, difference can be gained by "switching oil"?

[As an FYI I've used Castrol GTX (in "High Mileage" form more recently) and she's as full of oil as she's supposed to be.]

Seeing as how the engine keeps doing all it can to keep working I feel that I should do anything I can to help it do so. Seems my "little engine" still thinks it "can" and isn't listening to anyone that says different...

Redog

I always ran 10w30 in my 307.

I said it before, I think your problem is beyond the oil grade issue

MDchanic

For the love of God, man, put some 20W50 in that poor car.

5W30 is the wrong grade for that type of motor, no matter what the manual says - they specified a grade too thin in order to squeak an extra MPG or two out of it to meet the new fleet mileage standards.

As Red says, I'd put 10W30 winter / 10W40 summer in that car with a fresh motor, and with almost 200,000 miles on it, I'd go thicker and use 20W50, especially in the summer.

I can see no reason to think the 5W would provide better lubrication at start-up.
In fact, it will drip away from the bearings much more easily when hot, while the 20W will tend to stick around more.

- Eric

Dave Siltman

For what it's worth try a mechanical oil pressure guage and REALLY see what is going on. The sending unit could be bad and giving false readings. As for the oil, I also agree with what the others are suggesting. I don't know about your particular weather, but 10-40 seems to be a reasonable choice even if the oil pressure is good. Hooking up that guage should take only minutes and will not cost much either.

Bill in NC

exactly! X2

OLD SKL 69

Even if you find that the sending unit is the real culprit, I would switch to a heavier oil as others suggested. I had over 225k on my 85 307 and ran 10w40 its entire life. Still ran strong with no leaks or knocks at that mileage.

Tucker442

You guys need to go to the API site and see whata oils do what, there is something about new oils not being good for flat tappet cams which is what all our older engines have, being a GM A tech until Oldsmobile kicked us to the curb, we used 5w30 in anything under 4 litres, or anything smaller than the 260v8. The 260 and up engines all got factroy 10w30 which is what GM called for, we just followed the leader. Personally I have 2 Olds Silhouettes here both with over 130 each and have used 5w30 their entire life, they still don't use any oil between changes, also have a 02 Alero same deal 110 on the clock 5w30 and even at 5k it's still full when I finally get it away from the kid to do some maintance. I do know the new 5w30 is great for roller cams which is what I have here but the older cars did have an issue. I have heard guys say that the Diesel 15w40 has everything that older engines need, the API numbers are something like SD SF SG Cd CE Cf, C being for Diesel and the S letters for Gas engines, check it out at the API site they have the real deal there