: 5W30 vs 10W30, pre 2000 Northstar 84 degree weather



mtflight
03-01-06, 04:59 PM
Question for the experts.


It ticks me off.

It has happened to me three times: the ding-dongs at the oil change place, and even dealership... put in 5W30 in my Eldo.

According to the manual, the car calls for 10W30 where I am (Texas) due to temperatures.

If temp falls below zero F, then 5W30 is recommended, else 10W30.

What does putting this incorrect oil over and over again do to my engine? Less protection at high RPMs, aka more wear?

I understand that the 2000+ Northstars use 5W30 because of a different head design.

What do I do?? The receipt says 5W30. Ugh. :rant2:

Dadillac
03-01-06, 05:31 PM
Check the upper level of protection for the 5w30 (I am not sure what it is). As long as it doesn't get any hotter than that, do not worry about it. I run 5w30 in everything I have owned for the past 15 years. Manufacturers do not have regional engines, so all N*'s for a given year are all the same. So if folks who live in Maine, who have a 2000 N* use 5w30, so can you. You just need to make sure the temperature doesn't exceed the oils ability.

Don

mtflight
03-01-06, 05:58 PM
Check the upper level of protection for the 5w30 (I am not sure what it is). As long as it doesn't get any hotter than that, do not worry about it. I run 5w30 in everything I have owned for the past 15 years. Manufacturers do not have regional engines, so all N*'s for a given year are all the same. So if folks who live in Maine, who have a 2000 N* use 5w30, so can you. You just need to make sure the temperature doesn't exceed the oils ability.

Don

I am more concerned with the physical changes in the Northstar in the year 2000 that changed the oil requirement to 5W30. It was not a retroactive change for Northstars, but rather a consequence of redesign in the valve-cam system with roller followers, vs hydraulic tappets.. or something like that.

I just want to know the reasoning of why this would be--there must be something to it. Why does the older design require a thicker oil at higher ambient temperatures?

I top it off with 10W30, but I would be much less worried if the folks stuck to what the oil cap says is required : 10W30

Ranger
03-01-06, 06:27 PM
I asked our old guru this once before, when I got my youngest daughter her '04 Grand Am. It calls for 5w30. If I recall correctly, the biggest reason for 5w30 is the (theortical) better milage and CAFE numbers GM can claim. I asked if I (she) would even notice the difference in MPG. I think he said it would be minimal. Since her car was the only one in the stable that used 5w30 I elected to stay with 10w30. Even now that I have an '02, I am still using 10w30 in it.

davesdeville
03-01-06, 09:50 PM
It will cause slightly increased cam lobe wear AFAIK. Definately not a big deal, I just wouldn't run 5w30 for 100k miles but a couple oil changes won't make a difference.

Dadillac
03-01-06, 10:01 PM
I do not believe that running a slightly thinner oil will cause cam lobe wear. The first number in the oil is the cold weather viscosity. Once the engine is running, and starting to heat up, that number is irrelevant. It is just easier to start in the cold am's. I could be wrong (wouldn't be the first time), but wasn't GM a proponent to 10w30 in all of thier engines? I remember having a Chevy back in the mid 80's. It called for 10w40. A bulletin came out, stating that 10w40 could damage the engine, and start using 10w30. I am pretty sure GM stuck with that for a long time. With the exception of special engines (factory high hp, turbo'd, etc) you can pretty much use any viscosity you want to. Just make sure that the temps fall into the range that you will be driving in.

Don

JohnnyO
03-01-06, 10:01 PM
The majority of vehicles call for 5w-30 in recent years, so lube shops usually keep a bulk tank of it which is much less expensive to buy that way and pump it in to your engine from a hose. The dealer did the same with my Sport Trac and 5w-20, it's one of the engines that Ford specifically DOES NOT recommend 5w-20 for, and they put it in anyway since that's what's cheap (for them). I got my first four oil changes free, but this is one reason why I prefer to change my own oil.
2000-up N* says 5w-30 is okay, but if you want, insist on 10w-30 and watch them put it in. If they say no, then take your business elsewhere. Or buy some ramps and a drain pan and do it yourself. I can do it myself in way less time than waiting my turn at the Qwicky-Lube, but I realize some people may live in a apartment or townhouse where you're not allowed to do that stuff.

Ranger
03-01-06, 10:17 PM
I do not believe that running a slightly thinner oil will cause cam lobe wear. The first number in the oil is the cold weather viscosity. Once the engine is running, and starting to heat up, that number is irrelevant. It is just easier to start in the cold am's. I could be wrong (wouldn't be the first time), but wasn't GM a proponent to 10w30 in all of thier engines? I remember having a Chevy back in the mid 80's. It called for 10w40. A bulletin came out, stating that 10w40 could damage the engine, and start using 10w30. I am pretty sure GM stuck with that for a long time. With the exception of special engines (factory high hp, turbo'd, etc) you can pretty much use any viscosity you want to. Just make sure that the temps fall into the range that you will be driving in.

Don
Don,
You are correct on all counts. My father had a '79 Ford that I ended up with years ago. He was meticulaous about maintanence and always changed oil (10W40) at 3K. At about 56K I had to pull it down and R &R the camshaft and lifters. Two lobes where worn down and the corresponding lifters were dished. The inside of that engine looked like it was filled with pudding. I always suspected that it was the 10W40 and never used it again. Infact, I wouldn't use multigrade for years afterwards. The guru had confirmed my suspicions many years later. That was the reason for the bulletin. Fortunately, todays oils are much better.

Rob S
03-02-06, 12:01 AM
Don,
You are correct on all counts. My father had a '79 Ford that I ended up with years ago. He was meticulaous about maintanence and always changed oil (10W40) at 3K. At about 56K I had to pull it down and R &R the camshaft and lifters. Two lobes where worn down and the corresponding lifters were dished. The inside of that engine looked like it was filled with pudding. I always suspected that it was the 10W40 and never used it again. Infact, I wouldn't use multigrade for years afterwards. The guru had confirmed my suspicions many years later. That was the reason for the bulletin. Fortunately, todays oils are much better.

Years back, the dino oils had wax in them, hence the sludge build up you see in older engines. They dont do that any more.
If 5-30w was used in my STS, I would drain it and go with the 10-30. This is why I do all my own maintence and repair's. I just dont trust anyone else wrenching on my auto's.
On a side note, I have read that Synthetic Oil is not recommended for the N* engines so stay with Dino oil.

Ranger
03-02-06, 12:49 AM
I don't believe it was the "wax", if that is what it was. 10w40 needed more of what ever the word is that escapes me at the moment, that make it act like a 40w when hot and a 10w when cold than a 10w30 did. That addative (maybe wax) is what caused sludge. Infact not long afterwards, the big 3 made use of 10w40 a warranty breaker I believe. A few years later I removed the heads on my HT4100 to R & R gaskets at about the same milage. I used straight weights back then. It was spotless. Nothing worse than the inside of a tranny pan. The difference between the two was unbelievable.

Rob S
03-02-06, 01:02 AM
I don't believe it was the "wax", if that is what it was. 10w40 needed more of what ever the word is that escapes me at the moment, that make it act like a 40w when hot and a 10w when cold than a 10w30 did. That addative (maybe wax) is what caused sludge. Infact not long afterwards, the big 3 made use of 10w40 a warranty breaker I believe. A few years later I removed the heads on my HT4100 to R & R gaskets at about the same milage. I used straight weights back then. It was spotless. Nothing worse than the inside of a tranny pan. The difference between the two was unbelievable.

The new one's wont sludge up like that, it was the wax that caused that years ago. Now the weights have more to do with Temp and cold flow as well as what the engine was designed for, sludge isnt an issue. Cold weather start up wear is the biggest culpret. Also, keep what the engine requires in the manual in it, it goes along with oil passage's and oil pump volume.

chevelle
03-02-06, 03:01 PM
Just to clear up a couple of things....

The 93-99 Northstars have direct acting, rubbing element tappets. Those engines are spec'd for 10W30 oil (except for cold starting in very cold weather) to provide an adequate hydrodynamic bearing film thickness at the cam lobe interface at LOW RPMs. The cam lobe operating against the lifter interface actually does form a hydrodynamic oil film as it lifts the tappet. Slightly thicker or higher viscosity oil improves the hydrodynamic bearing film thickness and prevents wear on the cam lobe. This is most important when the engine is hot (thin oil) and idling (low RPM). At high RPM the speed of the lobe against the tappet creates a thicker oil film but at low engine speeds the time vs. load is much greater so the bearing film gets squished thinner so the thicker oil helps.

Using 5W30 oil in the 93-99 engines is not a guaranteed failure....but the recommended 10W30 oil provides extra insurance against eventual cam lobe wear.

The 2000 and later Northstars still have hydraulically adjusted (automatic) tappets but the tappet design changed to a roller finger follower. The rolling element at the cam lobe interface reduces friction considerably and also reduces the tappets dependency on the lubricant quality to live. The use of 5W30 oil is specified for the 2000 and later Northstars since it will reduce friction and improve fuel economy in the rest of the engine and the tappets specifically do not require the thicker viscosity anymore.

The issue with the 10W40 oils back in the 70's and 80's was not wax..... The early multivis oils such as the infamous 10W40's of the 70/80's contained very high concentrations of viscosity improvers to meet the wide spread between the "10" and "40" specifications. Unfortunately the viscosity improvers back then were relatively poor quality and the long chain polymers used for VI would break down in high temp areas causing varnish and carbon deposits. Ring belt deposits and stuck rings were common on engines back in the 70/80's that received a steady diet of 10W40. It was the VI packages causing the problems....not "wax". The current oils, rated SL or SM for API performance, use totally synthetic viscosity improvers so there is little or no concern over the use of multivis oils and the 10W40 oils in general. The concern over 10W40 oils is a holdover from the problems of the 70/80's with those oils. Current oils are perfectly fine as evidenced by even the heavy duty diesel oils being multivis without any problems. Ever notice that there were never any diesel rated oils that were multi-vis (and especially not 10W40!!) back in the 70/80's???

chevelle
03-02-06, 03:03 PM
Question for the experts.


It ticks me off.

It has happened to me three times: the ding-dongs at the oil change place, and even dealership... put in 5W30 in my Eldo.

According to the manual, the car calls for 10W30 where I am (Texas) due to temperatures.

If temp falls below zero F, then 5W30 is recommended, else 10W30.

What does putting this incorrect oil over and over again do to my engine? Less protection at high RPMs, aka more wear?

I understand that the 2000+ Northstars use 5W30 because of a different head design.

What do I do?? The receipt says 5W30. Ugh. :rant2:



I wouldn't worry about any problems but if you want to stop the practice you could return to the place that did the oil change and show them the correct oil spec in the owners manual, service manual, etc....and demand that they drain and fill with the CORRECT oil. Maybe they would remember next time....LOL.

mtflight
03-02-06, 03:27 PM
Thank you for your responses, most insightful, and exactly what I was looking for. I like the forced corrective measures suggestion, chevelle, and will take action!

Cheers!

mtflight
03-02-06, 05:00 PM
I wouldn't worry about any problems but if you want to stop the practice you could return to the place that did the oil change and show them the correct oil spec in the owners manual, service manual, etc....and demand that they drain and fill with the CORRECT oil. Maybe they would remember next time....LOL.

What is the world coming to? I spent 10 minutes on the phone talking to the service advisor, and he was so overconfident about 5w30 being ok because of the new api ratings blah blah.

They only stock 5w30, and would have to "special order" the 10W30. They will "comp" the next oil change, but I need to bring my own 10W30 since otherwise they have to special order it.

What BS. Oh, and they also overfilled it last time (above the MAX on the dipstick).

JohnnyO
03-02-06, 09:40 PM
Dittos what Chevelle said about the viscosity improvers back in the 70's-80's. I worked at an Olds/Cadillac dealer then and I remember in 1984 getting a letter from GM saying to stop using 10w-40 oil because the viscosity spread was too wide and the oil wasn't performing like it should. Today's oils would likely be fine, but back then they told us to use 10w-30. Stupid of your oil change place not to stock ANY 10w-30 though. I'd go somewhere else or do it yourself.

Patrick7997
03-03-06, 01:03 PM
They did that to me once....

I drove the car back the next day and demanded they change it back out. After brief & mild protestations, they drained it & refilled it with 10w30.

5w30 seems to be the "default" setting at those places now, though, so you have to specify....

I agree with Johnny O, unless I'm too busy or too lazy.... by the time I sit there in line for a half hour, I could have drove it up on my ramps and done it myself. Plus it saves a pile of money.

boricuacaddy
03-03-06, 01:25 PM
The funny thing is, I take my Caddy to the dealer to have my oil change, and they always put the 5w30 in my car. I would think they should know what is recommended for my car. Next time I go back I will make sure to talk to the service rep. about using the correct oil in my car.

David

dkozloski
03-03-06, 02:35 PM
Flat tappet cam followers were the last stumbling block to adopting 5W-30 oil as a fuel saving measure industrywide. The difference in milage is small but substantial enough that the car makers decided it was worth the trouble to improve CAFE milage. Flat tappets were the last high pressure sliding contact left in the engine design that called for the 10W spec under certain conditions.

Ranger
03-03-06, 05:32 PM
The thing that baffles me is that 5W30 & 10W30 are both 30 weight after a very short warm up period. So where is the fuel milage savings? I'm sticking with 10W. I just feel better about it. Is the "old school" starting to show again?:)

Dadillac
03-03-06, 07:12 PM
The thing that baffles me is that 5W30 & 10W30 are both 30 weight after a very short warm up period. So where is the fuel milage savings? I'm sticking with 10W. I just feel better about it. Is the "old school" starting to show again?:)
We both have the same engine. On the coldest of days, like -5*, my car, with 5w30, will start a little easier and quicker than yours, using 10w30. All of this oil talk is ludicrous. It is amazing how much stock people put into "oh my God, what oil should I use". It amazes me. I stand by my statement above. With a few esceptions, 5w30 can be used in about every engine produced since about 1985. It really isn't that critical.

Don

Ranger
03-03-06, 07:52 PM
I agree Don. Oil wars have been started over the question. Hell, have you ever checked out bobistheoilguy? A whole site dedicated to it. They have 5W30 running through their vains. They obsess about it.

dkozloski
03-03-06, 08:50 PM
The way I heard it sonny, 5W-30 doesn't provide sufficient protection during the first few minutes during a cold start for a flat tappet cam. Once it's warmed up all is fine. 60 years ago we used straight 5W in the winter and got away with it for a while. At the mid temp range where the oil normally operates 5W-30 is still slightly thinner than 10W-30. I admit it sounds like stomping on pissants while elephants are running up and down the halls. This is what the engineers claim and I'm just passing it on.

Zorb750
04-08-06, 02:46 PM
I'm partial to 5w40 PAO (Mobil1) synthetic (not that Castrol Syntec Swill) myself. It's spec for most better Euro cars for a reason you know.

Your initial circulation is quick and it doesn't thin as much as 10w30 at high temperatures. Play with it at higher RPMs, especially with the windows open. It sounds smoother, more harmonious. Seriously! Sometimes in the summer I used to run 15w50 Mobil1 on it when I took it to the track, but I would notice the smoothness benefit coming home so I started doing that during the summer all the time, until Mobil1 came out with the 5w40, now I am very happy with it. For you "old school" guys, 15w50 mobil1 has a lower pour point than 10w30 dino juice anyway, not that I was running it in the cold.

That's my vote.

mtflight
04-09-06, 01:15 AM
I'm partial to 5w40 PAO (Mobil1) synthetic (not that Castrol Syntec Swill) myself. It's spec for most better Euro cars for a reason you know.
... Play with it at higher RPMs, especially with the windows open. It sounds smoother, more harmonious. Seriously!


Sounds like the placebo effect. :rolleyes:

Zorb750
04-09-06, 02:38 PM
Try it and see. Any time you drive the oil pressure up, you also smooth out any internal vibration related issue, no matter how slight.

Also, try reving it, letting it come back down, then taking it up to 3000 RPM next to a brick wall. Tim Horton's drive throughs late at night work very well, after you get your coffee just in case you piss someone off. The brick wall makes every little noise more evident, especially the high pitched ones.

I mean it. I'll bet you a case of 5w40 oil.

:coffee:

Zorb750
04-09-06, 02:42 PM
On the point of oil thinning, it's true in the case of conventional oils that 5w30 may thin a bit more at high temperatures.