5w-20 Confusion

[Mustang Man]

This is my first post here. I have been lurching for awhile now and enjoy the knowledge present here.

I recently bought a low-miled 2001 Mustang GT. I had a 1998 model before that. The 98 used 5w30 and the 2001 claims 5w-20 is needed. Both have the 4.6L engine. There is nothing different between the engines from what I can tell.

It is time for me to change the oil for the first time since I bought the 2001. I honestly feel the engine should have a 30 weight instead of a 20 weight oil. I am leaning towards 0w-30.

0w-30 makes sense to me. 5w-20 is probably OK for a 4 banger or a 6 cylinder non-performance engine, but I doubt it for a V8.

I read the Dr. Haas articles. I am well aware most engine wear occurs at start-up so it makes sense to use the lightest weight oil possible for that, but the engine is at peak operating temperature quickly. I just don't feel good about running a 20 weight oil in my car. Heck all the GMs use 5w30. I am astounded Dr. Hass runs 20 weight in his car. I guess he can afford a new engine when he reaches thermal breakdown.

So why the 5w-20 recommendation? CAFE credits that can be used to offset Ford vehicles that don't have good economy and can be sold to other car companies?

I am debating between Mobil 1 Green Cap and Castrol German 0w-30. I am betting the CG is thicker than the M1.

I am just looking for opinions and guidance. I need to change the oil soon. Thanks in advance

I did use the search feature of course, but all the 5w-20 questions like mine seem to pertain to cars with 4 and 6 cylinder engines. Nothing I could find on higher performance engines.

 

[demarpaint]

Welcome to Bitog!

There is a ton of info on this very topic. Any idea what oil was used in the past? If so you might want to continue with that.

If it were my car I'd use what Ford suggests, for that model year. Either way 5W20 or 5W30 you won't ruin the engine. Do some reading here, and decide based on that. I can tell you this, after reading here you might just end up tossing a coin. Heads 5W20, tails 5W30.

 

[bdcardinal]

The 5w20 was done for CAFE. Your car will run on any 5wXX, 0wXX and be fine.

 

[Mustang Man]

Thanks for the quick replies! Yeah I am pretty much set on using 0w-30. 5w-20 just seems weak to me in a V8. If it was a 4 cylinder then I would be OK with running 5w-20.

I can easily get Mobil 1 0w30 Green Cap at Wal-Mart in the 5 quart jug for $22. That and an extra quart for another $6 and a $4 Motorcraft oil filter. $32 for a synthetic oil change using doing a 7500-10K OCI is good in my book.

I didn't see Castrol German 0w30 at Wal-Mart and my local Autozone only had one bottle of it on the rack. Behind it was all American Castrol 0w-30. I asked if they had more and they said they didn't expect to be getting any more. Is it being phased out?

 

[OVERKILL]

You can also run M1 0w40, which is only slightly heavier initially than GC 0w30.

 

[DreamerGT]

mine does just fine with 5w 20

 

[Mustang Man]

Originally Posted By: OVERK1LL
You can also run M1 0w40, which is only slightly heavier initially than GC 0w30.

I guess you live up to your name, lol. Would a 40 weight be "OVERKILL"? I could understand running it in an older engine that was worn down a little. My 2001 Mustang has been barely driven and only has 76K on the odometer.

 

[Mustang Man]

Originally Posted By: DreamerGT
mine does just fine with 5w 20

_________________________
03 Crown Victoria PI, 5w30 Valvoline Maxlife,
02 Mustang GT, 5w-20 Pennzoil Platinum
Drive a hybrid I need your gas


I see in your sig that you have an 03 Vic PI. 4.6L engine right? So why are you using 5w30 in it instead of 5w-20 like you are in your Mustang with the same engine?

 

[SevenBizzos]

I only run 5w-20 in my '02. Have been the entire time. I believe they back spec'd the late 90's 4.6L to 5W-20 via TSB.

 

[Mustang Man]

Originally Posted By: SevenBizzos
I only run 5w-20 in my '02. Have been the entire time. I believe they back spec'd the late 90's 4.6L to 5W-20 via TSB.

Yes they did. I am positive that was done for CAFE as opposed to being a better oil weight.

Oh on a side note, I am not meaning to start a CAFE debate here. I have seen threads here get ruined over that. But it is funny that a car that came with 5w30 is now all good to run a 5w-20 oil. It just seems to me there is more of a chance of thermal breakdown when running it hard.

 

[OVERKILL]

Originally Posted By: Mustang_Man
Originally Posted By: OVERK1LL
You can also run M1 0w40, which is only slightly heavier initially than GC 0w30.

I guess you live up to your name, lol. Would a 40 weight be "OVERKILL"? I could understand running it in an older engine that was worn down a little. My 2001 Mustang has been barely driven and only has 76K on the odometer.


M1 0w40 is a very light 40-weight; almost a 30. In certain applications, it shears to a 30 anyways. It has a huge amassment of manufacturer certifications and approvals, and is overall just a fantastic oil.

I've run it in my 5.4L (2002), as well, we are currently running it in our 2000 5.4L as well (another Expedition).

The 2V Modular engines spec 30 to 50 weight oils in the rest of the world. a 40-weight is a popular choice for them in Australia.

The new 3V Modular engines are the ones "designed around" a 5w20; and subsequently spec 5w30 in Australia.

 

[aquariuscsm]

If I ever buy a V8 Mustang (it`d be either that or a 370Z) it`s getting a 50 weight oil. The Ford GT is spec`d for a 50 weight. It`s not a CAFE regulated car,so imo Ford knows it`s going to be raced and driven hard,so CAFE doesn`t apply to it like all the typical mainstream cars.

 

[Gary Allan]

Quote:
But it is funny that a car that came with 5w30 is now all good to run a 5w-20 oil.


Cars used to have spec's of 20w-50 ..in the 70's. We're now in a new century. Any cars ..even HD pickups ..or even most of the diesels out there require 20w-50 anymore?

Something happened.

5w-20 has been OEM spec'd by Ford for almost a decade ...in just about everything. Any mass migration to the junkyards with premature engine fatigue?

Quote:
It just seems to me there is more of a chance of thermal breakdown when running it hard.


What are you calling thermal break down? If you mean oils getting thinner as they are heated, that happens to all of them regardless of visc. If you're talking about being "damaged" or fatigued, what makes you think that a contemporary 20 grade would be any more susceptible to this event than any other oil?

You do realize that while vastly improved, if you've been using a conventional 5w30 you've been using a 20 grade at some point in the interval, don't you? The only difference is that the contemporary 5w-20's are 5w-20's in the bottle instead of shearing in service.

 

[OVERKILL]

Originally Posted By: aquariuscsm
If I ever buy a V8 Mustang (it`d be either that or a 370Z) it`s getting a 50 weight oil. The Ford GT is spec`d for a 50 weight. It`s not a CAFE regulated car,so imo Ford knows it`s going to be raced and driven hard,so CAFE doesn`t apply to it like all the typical mainstream cars.


The Ford GT, and the GT500, which both spec 5w50, are also both supercharged. They make a LOT more heat than their naturally aspirated siblings and subsequently, likely need a greater "buffer" as well.

They have a higher specific power output, due to their forced induction, which of course plays a big roll too.

Oil temperature dictates what your "running viscosity" is. In a high-output, moderate displacement engine with a 6L sump, being fed by a blower that heats incoming air and turns the engine bay into a blast furnace, oil temperatures are likely quite high. High enough for Ford, in their testing to state "OK, this engine needs 5w50", when the rest of the family specs 5w20.

Ford has gone through a fair deal of effort in controlling oil temperatures, I believe it was Jim Allen on this board who tracks oil temps on a Modular while towing, and they are always relatively low. This is because Ford uses large sumps and factory oil coolers.

It isn't a matter of the engine just "working" with 5w20. 5w20 is just a grade and the viscosity you should be concerned about is the one seen by your bearings and other moving engine parts when your engine is working. And this viscosity is dictated by temperature. Ford has gone through extensive lengths to CONTROL this temperature by virtue of the aforementioned methods so that they CAN run 5w20 without risk of lubrication failure, even towing a camper through Death Valley.

Ford went through even greater lengths with the 3V engines; putting a higher output oil pump on the engine and a few other changes.

Why?

Well the 5.4L and 4.6L 2V engines were designed around a 30-weight. Factory oil coolers, 6L sumps.... And a 30-weight.

It was later tested by Ford that the setup would allow, in many applications, a 20-weight without issue. And so Ford back-spec'd those engines. But they were never DESIGNED around 5w20.

The 3V Modular engines WERE.

Now, when you step outside the naturally aspirated Modular world and into the land of forced-induction high performance, then the oil cooler and sump capacity are simply not enough. If they were, Ford would have spec'd 5w20 or 5w30 or even 5w40 for the GT500 and Ford GT. But they DIDN'T. Obviously, because, in their own testing, a 5w50 proved necessary.

So, why am I using a 0w40? Because the 2V originally spec'd a 5w30. The 40-grade oils, particularly the HDEO ones, are more "robust" than your run of the mill 5w30. And given the wide-range of acceptable grades that Ford has spec'd for the 2V Modular throughout the rest of the world, which includes 50-weights, I have no reservations running a 0w40.

Would I run it in a 3V? No. Ford spec's 5w30 for the 3V in Australia. That's a red flag to me that states they've done some serious testing and that's the BEST grade for that engine. Especially given that the Aussie's have no CAFE.

My two cents anyways.

-Chris

 

[DreamerGT]

Originally Posted By: Mustang_Man
Originally Posted By: DreamerGT
mine does just fine with 5w 20

_________________________
03 Crown Victoria PI, 5w30 Valvoline Maxlife,
02 Mustang GT, 5w-20 Pennzoil Platinum
Drive a hybrid I need your gas


I see in your sig that you have an 03 Vic PI. 4.6L engine right? So why are you using 5w30 in it instead of 5w-20 like you are in your Mustang with the same engine?


The valve seals are going so I went a little thicker to stop it from smoking at start up. But its not help alot so I will go with a thicker 10w 30 next time.

 

[38sho]

I don't get why they backspec'd older cars to use the 5w-20, when everyone just claims they use the 5w-20 to meet CAFE regulations.... why would that even matter on a car that is already 10-15 years old........

fact of the matter is, we've all seen Mod motors run for hundreds of thousands of miles on 20 weight oils. Same can be said for them being run on 30 and 40wt oils too! I don't think you can go wrong either way..... I'd probably run a good 20wt in it and see how it works out first, then work my way up if I don't like the results.

The way you keep mentioning thermal breakdown, I think you been watching too many Castrol GTX's commercials

also your vintage 4.6 isn't that high of performance. Some 2 liter 4 bangers out there will give you a run for the money. My 3.2 liter 6 banger will walk away from your car. They are running much harder to make more power from something smaller and rev up higher. I think of the big displacement, small HP v8's as more of a detuned, easy running engine, kind of like what you would find in a piston airplane.

The Ford GT engine is nowhere close to the same as a Mustang GT engine..... thats compairing apples to oranges, so many parts are different, the oiling system is different, the lubrication passages are different........

 

[95busa]

2001 was the first year for the PI (performance improved) heads on the 4.6l V8. I think there were a few other tweaks besides the heads, but the motor was definately changed somewhat between 98 and 01. I believe we are talking about a 20hp or so difference.

 

[CROWNVIC4LIFE]

Originally Posted By: DreamerGT
mine does just fine with 5w 20

+1

All our 4.6 panthers love the 5w20 Motorcraft...Thats in jungle heat and nightmare traffic.

When I had my 99 4.6 panther I went from 5w30 to 5w20...It turned out the car liked the 5w20 alot better...The car had 200K miles on it when a hurricane totaled it out for me.

But if you want to use 5w30 it will be just fine also

 

[bdcardinal]

Originally Posted By: 38sho
I don't get why they backspec'd older cars to use the 5w-20, when everyone just claims they use the 5w-20 to meet CAFE regulations.... why would that even matter on a car that is already 10-15 years old........


They were able to show increased MPG on older models so the CAFE based on the past 10 years, remember the modular motor came out on the 1991 Town Car.

 

[bdcardinal]

Originally Posted By: 95busa
2001 was the first year for the PI (performance improved) heads on the 4.6l V8. I think there were a few other tweaks besides the heads, but the motor was definately changed somewhat between 98 and 01. I believe we are talking about a 20hp or so difference.


PI heads were on 99+ Mustang GTs, 2001 on the Panther platform.