Did I make a mistake going with 20W50 on my 170k+ engine?

CaifanSC

SCCoA Member
Altho it was freezing b@lls today I decided to change my spark plugs, wires and oil on the 94. I did it, primed the engine, hooked the inertia switch back up and the car starter really rough. After a couple starts it idles ok, but a bit shakey. It also sounds really loapy which is kinda cool, but considering It didnt sound like that before makes me worry. Its about 30* outside, so im wondering if the thicker oil might hve something to do with it.

Car has over 170k miles and i think i had started hearing very slight kocking when I first start it in the morning...so i thought running a thicker oil might tighten things up a bit. Any suggestions?
 
Youve probably opened a big can of worms here but here goes anyway. Ive used Castrol 20w50 in all of mine and havent had any troubles yet. Weve had about 2 weeks of 20-30 degree nights and Ive had no trouble yet with my oil. One of mine Ive got 186k on it of which Ive put almost 100k of it on it with the same oil.

S
 
I use Valvoline 20w50 race blend in mine except for winter, then I switch to 10w40. The 20w50 does get real thick in the winter and probably isn't a good idea when outside temps get below freezing.

David
 
so whatcha think, im still able to drain it and put 10W40? Typically I also use a quart of lucas oil additive but seeing as to how thick the 20w50 is, i didn use it this time. With the 10W40 should I also refrain from using it?
 
so whatcha think, im still able to drain it and put 10W40? Typically I also use a quart of lucas oil additive but seeing as to how thick the 20w50 is, i didn use it this time. With the 10W40 should I also refrain from using it?

If it were me, I'd drain two or three quarts and replace them with 10w30 of the same brand. I don't know anything about or use additives like Lucas...I just change the oil and filter every 3000 miles or sooner.

David
 
I'd check to see if the wires are all on right and pushed all the way on the spark plugs.

Even if the oil could do that within 5 min it would run normal
 
I agree with Damon...the thicker oil won't make it idle rough or start shakey...more likely something related to the plugs or wires. If the wires are stock style Motorcraft they can easily be damaged just changing plugs.

David
 
20W50 made my 83 Tbird 302 idle rough on a cold startup. But only until it got a little heat going. My mechanic who built the engine swore by Valvoline racing 20W50, but I couldn't take the morning cold starts. So I went to a 10W40 for winter and it quit idling rough. As long as it was above freezing it wouldn't do it, but below it was a rough noisy start.
 
first I've heard of that...although since I'm in Florida we don't generally see cold enough weather to make any difference but we don't do alot of 50W oil changes. We do use 5w20 etc castrol in about 25% of our oil changes at the shop and don't see any significant difference. I am in firm agreement though with the every 3000 change out. or 6000 with synthetic. I'd look for something loose though. I was curious weather you were throwing any check engine lights.
 
so here is the deal.....

The oil will NOT affect the way it runs, when it is warm. When it gets cold, the oil will have a harder time getting to where it has to go. One of those places are your lifters... If you think about this for a second, you will see where I am coming from. You use oil to pump up your lifters ,unless they are solid's. The cold oil will not pump up the lifters as well, hence the rough running when the engine is cold.
Now if you say that it runs better when it is warmmed up then look at the oil. If it still has issues, then look elsewhere for something wrong. I run 15w-50 in all my trucks with no trouble. This is even when it is really cold like today when it was -14 degrees....
Hope this helps some and also clears up this issue of heavy oil's.....Good luck and look at your plug wires.....Rich
 
check your maf wires i hit mine once and it idled like it had a big cam pushed the wires in and it ran fine just a thought :)
 
I run 15-50 mobile 1 in my GN, and Merkur. I have no problem with start up, and it gets cold here too. I am still learning about my SC, and I am using 10-30 synthetic with additves. If you run thick oil, and it is cold outside you need to crank the motor a couple times without letting it start all the way to get some oil to the main's before it runs. The 3000 mile oil change in my opinion is a bunch of bunk. The quick change oil places started it, and now it seems the whole world agrees. Well the auto manufacturers don't, and they have the big power train warranties to stand behind.If you reseach the science behind the oils, you will find that the oil manufacturers have some very cautious longevity estimates for their products that are way over the 3000 mile mark. With Mobile 1 I run 5-6000 miles, then change the filter, add a quart, and drive another 5-6000 miles. If you are really concerned, get your oil tested. Just my thoughts. I don't stand in judgement of anyone who feels the need to change the oil in a high performance car every 3000 miles. If you are racing hard you may want to change oil after each race. But for the majority of engines out there a 7500 mile oil change with regular oil, and 12000-15000 with a good synthetic is reasonable, and prudent. Later
Danny
 
It's a wire, plug or a coil pack. Pull them one by one and when you get to the one that doesn't make it worse, you've found the culprit. You more than likely will not get a check engine light.
 
This weekend i'll probably drain all of the 20w50 and switch it to 10w40, i dont think i need to change the filter I'll double check plugs and wires too.
 
We've all done it-
Clocks tickin,
cold outside
"all thats left is to throw on the wires"
1,2,3,4,5,6........
"DONE! lets run this thing and get some heat goin'"
?????????

ahhhhh......1,2,3,4,6,5.
vvvvrrroooommmmm.
Check the plug wires!
good luck,
jj
 
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