My Granddad has a 1999 Mercury Marquis with the 4.6. Recently he checked the oil and it was a quart low so he added a quart of 10w30. Just after that it started knocking slightly. Would the wrong oil cause this? Thanks! Benjamin

 

I'm taking a slightly educated guess here, but I believe the specs. from Ford (Merc.\Lincoln) call for 5W30. If he (your Grandad) had ALL 5W30 in the motor (engine\crankcase) and he added 10W30 it MIGHT (possibly) cause some noise or A noise, though I would think it would be very slight or minimal (barely audible, if at all humanly audible) and should (again - I would think) minimize or lessen as the oil got warm and was circulating well. I believe (in extreme novice or layman terms) you could say that the 2 (two) different weights of oil would sort of "confuse" the tolerances and tight "machine-ings" of the internal metal parts (i.e. one second a 'lighter' oil is pumping, the next instant a 'heavier' weight is making the rounds). I'm sure someone else could explain it better (and certainly alot more technically) than I'm seeming able to do, but this MAY be the problem. Always remember, mixing different "brands" together is generally o.k. - mixing different "weights" is SPECIFICALLY not appropriate. Just always know the weight of the oil that IS IN the motor and ALWAYS "add" the same weight. You can "change" weights when you do a COMPLETE oil change (seasonal change-over), lighter or heavier, depending on the expected\anticipated up-coming weather temp.\climate conditions. Hope this helps and I hope I didn't waste your time telling you something you already knew. If it didn't (help) and I did (waste your time) someone is bound to come along thru here and straighten us BOTH out! Best of luck to your Grandad (and his Merc.)!

 

Hi. Sorry I haven't responded before now...my computer was down. He has all his vehicles serviced at Ford so I guess they would have the right kind of oil in there to start with? (5W30) Personally, I don't trust ford's service department or any other quick lube for that matter. I'm going to do my own servicing when I get my Ford. I was thinking the same thing about mixing different weights of oil. That is probably why. I think he took it to ford and had them check it out and maybe an oil change done so it is probably fixed now. Just wonder what it was that was knocking.. Thanks for your response! Benjamin

 

Really, the oil would soon be well mixed and consistant. It's not like you would get a "slug" of 10W30, then a "slug" of 5W30. I can't imagine that this would make a noticeable difference.

MrBSS

 

I can't imagine NOTICING a difference either, at least not anytime soon - but obviously there would be, over the life of the engine, that is, the shortened life. I agree the oil would be well mixed very quickly - however NOT consistent. Once fully warm, I then do not believe there would be a difference, both viscosities being "30" on the 'high-temp' side. The tight tolerances and clearances of an modern engine WOULD notice the difference on 'cold' start however and this is a more critical factor in considering\adding weights of differing viscosities - over the life of an engine. I'm really going out on a limb now, but I think it's similar to why they want to know ones blood type before they do a transfusion - though some types will mix, others will shorten ones life - rather quickly. My 2 cents

 

[updated:LAST EDITED ON 03-Sep-02 AT 11:39 AM (EST)]You're getting a little far afield here, but if we get into the chemistry, blood is largely a suspension while motor oil is pretty much a solution (at least until it gets contaminated). As a solution, it would be consistent and take on properties more or less averaging that of its components. I don't believe there would be any reaction between components.

MrBSS

 

Can I offer up a simple solution -
Change the oil, if it keeps knocking, then the problem is the motor. If not, then maybe a weird oil issue.
We had a "off-make" car which would start tapping in valve covers when the oil would break-down = change time. Also, I have known CHEAP oils to cause severe engine damage over time. So ALWAYS use a good oil.
My Two Cents!

Keep it Rubber Side Down!

 

[updated:LAST EDITED ON 05-Sep-02 AT 01:27 AM (EST)]Good practical advice - requesting your two cents again - what CHEAP oils are you referring to - that you 'know' of?

 

In terms of "Cheap" oils, (in my un-professional opinion) I am referring mostly to stuff that is little known or not known at all. Basically, choose a good Name Brand - I personally like Valvoline - never had any trouble with it. Quaker State USED to be a good oil - not sure what happened with it - it seems to cause sticky valves these days. Penzoil is not bad, but they use way too many detergents and additives which (in my own opinion) takes away from the lubricating value - if you don't believe me, find some one who is running it and pull the dipstick and admire the frothy mess on the stick. Castrol - not bad and it has a following. My best advice is to ask around at various garages and ask what they use & don't use.
Hope this helps!
Cheers.

Keep it Rubber Side Down!

 

How can cheap oil damage engines if it passes the sj or the newer sl spec?

I recently bought 3 cases of citgo "superguard" 5w-30 for my ranger
because they had a special I got it for about 35Cents a quart.
(normal price is 1.29qt)
Heh, gotta love buy one get 2 free... sales with double coupons.

Another question does anyone know what oil citgo actually is?
I know alot of companies just buy the oil and put it in their bottles.

Rand



On another note That extreme oil thing was funny

 

Most "off brand" oils are from one of the big oil companies with a different bottle. If it passes the standard then it is a good oil, as per some tests with NYC taxi cabs that was talked about somewhere here.