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

mtflight · #1 (**permalink**) 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.

Dadillac · #2 (**permalink**) 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 · #3 (**permalink**) 03-01-06, 05:58 PM

Quote:

Originally Posted by Dadillac

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** · #4 (**permalink**) 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 · #5 (**permalink**) 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 · #6 (**permalink**) 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 · #7 (**permalink**) 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** · #8 (**permalink**) 03-01-06, 10:17 PM

Quote:

Originally Posted by Dadillac

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 · #9 (**permalink**) 03-02-06, 12:01 AM

Quote:

Originally Posted by Ranger

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** · #10 (**permalink**) 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 · #11 (**permalink**) 03-02-06, 01:02 AM

Quote:

Originally Posted by Ranger

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 · #12 (**permalink**) 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 · #13 (**permalink**) 03-02-06, 03:03 PM

Quote:

Originally Posted by mtflight

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.

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 · #14 (**permalink**) 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 · #15 (**permalink**) 03-02-06, 05:00 PM

Quote:

Originally Posted by chevelle

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).