View Full Version : 20w-50 oil in my SC?

08-01-2002, 02:30 PM
Hey guys. My crank is starting to bang around a bit, and my mechanic and I think it would be alright to put 20w-50 weight oil in the old girl. You know, the thicker weight oil quiting down the knocking (maybe). So anyway... I was wondering if any of you thought this would be bad for my motor. Thanks again.

fast Ed
08-01-2002, 03:09 PM
Well, if the motor is getting to be NFG anyway, it's worth a try. Many guys on the board including myself are running fairly heavy weight oil in the summer time ... I'm using 15W50 Mobil 1. The thinking is that when the SC motor is under boost, you're looking at almost diesel-like compression ratio.

It shouldn't harm anything, and hopefully it will quiet the motor up a bit too.

Ed Nicholson

j rick kirby
08-01-2002, 03:09 PM
It will tighten up the bearing clearances and raise the oil pressure.This is good for a high mileage motor.

David Neibert
08-01-2002, 05:33 PM
I have Valvoline 20-50 in my engine now, mainly to protect the bearings. And yes it will help and older engine.


08-01-2002, 06:31 PM
im also running 20w-50 oil in my SC its also Valvoline vr1 racing oil..

i would use it if i where you!


08-02-2002, 04:34 PM
Thanks guys.
I didn't figure it would hurt anything! ... but it never hurts to double check:)

08-02-2002, 09:55 PM
I use 20w 50 Castrol Syntec in mine. Anytime you've got lots of horses per cylinder (like an SC), you should use a thicker oil to make sure it doesn't squeeze out under all that pressure.

Mike Farish
08-06-2002, 11:15 PM
I'm the guy with the High Oil Consumption SC, currently a qt in 500 miles....using Factory Recommended 5W30. Since signing on a few months ago I have read many guys running thicker oil. When my son owned the car, the shop tending to the car was filling it with 20W50 due to oil consumption. My brother, at Ford Dealership in Va. told me to get that stuff out of there. Boy, you get so many conflicting stories. My bird only has 45K miles. I just changed mine 300 miles ago to a 1st time use of 5W30 Mobil Synthetic Blend. I wasn't ready to be so bold as to go directly to full synthetic. So far I have added less than 8 ozs which is half of previous consumption rate. Digitalchaos has me venturing into the Synthetics so maybe he's "right on" to reducing my consumption. I will provide a 1000 mile report off my "High Oil Consumption" thread.


08-08-2002, 07:59 PM
I use 20-50 RedLine because of the heat around here. Never a problem. I change it every 5000 miles. It never needs to be topped up between changes. I started using it at 30,000 miles. I have 65,000 miles now. I like the lack of oil consumption and the knowledge that the oil is protecting my engine in 110 degree summer heat. One big problem...cost. I pay almost $8.00 a quart plus shipping!

Mike Farish
08-08-2002, 10:42 PM
Thanks West Coast Ghost for your reply. Did you ever use the factory recommended 5W30 and did you ever consume oil?

Also to anybody...The factory recommends 5W30 due to tight clearances and initial start-up. I read where so many guys are using 20W50 and I assume with no problems. Why isn't it factory recommended? Am I using oil just simply because it's so thin and I'm forcing it out? I'm an older guy that doesn't race anymore and I hardly ever put the car thru hard acceleration. I assume I'm not consuming as much oil since switching to 5W30 Syn Blend because it doesn't break down like regular 5W30. Would full Syntetic mean even less consumption or do I just go to a slightly heavier oil? Also I see the "Lucas" oil products ad on the Speed Channel frequently. Is this stuff for real? When I had the car in the shop right after buying it back from my son I got an oil flush because the mechanic smelled an additive in my oil. He also recommended to never add an additive. So many opinions out there, aren't there?

I'm open for suggestions from anyone and thanks in advance.


08-08-2002, 11:42 PM
20w-50 is good choice if you live in the warm states, by this I mean, that it'll never be so cold that lakes freeze. Then you're safe to go with 20w-50, otherwise that's too thick.

08-09-2002, 08:16 AM
Yeah, I used both 5-30 and 10-30 when I purchased the SC in '97. And, yes, I had to top up between 3000 mile oil changes. I'm no oil expert but I believe synthetic oil had a higher flash point than dino oil. Thus less of it burns off between changes. Again, I use it because of the heat around here and have been very satisfied, except for the cost.

David Neibert
08-09-2002, 09:22 AM

A portion of the oil you are consuming is probably from the PCV valve and breather system. The one on the passenger side rocker cover is so close to the intake plenum it actually sucks oil into the intake. If you were to loosen your lower IC tube you will most likely find several ounces of motor oil in the tube.

It's a double wammy, you loose oil and the oil getting into the intake causes detionation to occur sooner, robbing you of performance.

I installed a fuel filter between the PVC valve and the intake plenum to trap the oil. It works pretty well at catching most of the oil and will usually fill the fitler between oil changes. Here is a picture.


On a recent road trip mine used a full quart between fillups because the PCV valve had been pulled out of the rocker cover.

No offense to your mechanic, but most of them don't have a clue when it comes to these cars. There just are not enough of them on the road for dealers to become familiar with them.

I would suggest you replace the PCV valve and make sure the hose attaching the breather on the drivers side cover is connected to the air intake tube between the MAF and TB. The hose connects to the bottom side of the air intake tube and runs under the supercharger snout to the drivers side rocker cover and is very hard to see.

I'm only using the 20-50W in summer and use 10-40w in the winter.

Good luck, David

Mike Farish
08-10-2002, 08:03 AM
Thanks David, Sam and Jpaitala for your responses. I continued this discussion in a new thread "20W50 vs Fact Recom 5W30.


08-10-2002, 02:52 PM
You're welcome. It's always nice to help, even for a little!!