5W-20 or 5W-30?
5th Gear Member
Joined: Mar 2007
Posts: 3,062
From: Florida
RE: 5W-20 or 5W-30?
My rule of thumb is when the manufacturer who has spent who-knows-how-much (millions?)on R&D to design a vehicle/engine, and has MANY dollars to potentially lose on warranty claims of engines gone bad... when they say to use 5W20, I use 5W20. 
1st Gear Member
Joined: Mar 2008
Posts: 137
From: Michigan
RE: 5W-20 or 5W-30?
I've used Motorcraft 5W20 in my 2001 V10 Excursion since it was new. 65,000 miles of towing a very heavy trailer (~9,500lbs) and zero issues. Stick with what the mfg. recommends, IMO.
6th Gear Member
Joined: Nov 2007
Posts: 6,193
From: Montaner
RE: 5W-20 or 5W-30?
Are you aware that I spent about 10 years doing engine development with Ford Motor Company, including being the systems engineer on the 2003 Aviator and 2005 Mustang V8s?
And understand that I'm not saying that 5W-20 is not going to instantly do damage. But suffice it to say I've seen and been involved in a LOT of development on these motors, and my personal opinion is that I would never run 5W-20 in a modular motor. Regarding your "spec oil" comment, you need to look at what else governs this recommendation.
Who to believe!?! [&:]
4th Gear Member
Joined: Apr 2007
Posts: 1,323
From: So Cal
RE: 5W-20 or 5W-30?
ORIGINAL: svfetter
A lot of good discussion but one major point missed. The main reason 5w-20 is required on the 4.6 is the engine clearances. I learned that running a heaver oil can actually starve areas of oil. When an engine has enough miles and wear actually opens up the clearances, then a heaver oil can be safely used. Trick is, when have clearances opened up enough? Have never heard anybody speak to this. As my car is not a DD, but is a Sunday, and show car, I will be using the 5W-20 for quite some time.
A lot of good discussion but one major point missed. The main reason 5w-20 is required on the 4.6 is the engine clearances. I learned that running a heaver oil can actually starve areas of oil. When an engine has enough miles and wear actually opens up the clearances, then a heaver oil can be safely used. Trick is, when have clearances opened up enough? Have never heard anybody speak to this. As my car is not a DD, but is a Sunday, and show car, I will be using the 5W-20 for quite some time.
I have been getting different opinions about this. I have heard that 5w30 is actually too thick and it will cause clearance issues if you have been using 5w20. Bascially premature engine wear and oil burn. If you used 5w20 from the beginning you would need to stay with it and if you used 5w30 you would need to stick with that. The engine clearances between the piston/rings are very tight and precise.
On the other hand I have read online that 10w30 holds up better and 5w20 is used for mileage reasons. Since I have been using 5w20 i will stick to that because i dont want my clearances to change whatsoever in my engine; even if its minuscule.
So bascically if you have been using 5w20 i would stick with it since all your moving parts have sealed to that specific grade of oil and if you have been using 10w30 or 5w30i would stick with that.
After my engine build I am probably going to use 10w30.
6th Gear Member
Joined: Nov 2007
Posts: 6,193
From: Montaner
RE: 5W-20 or 5W-30?
After 3 HPDE events and getting an oil analysis done every time, by Blackstone Labs. I am going with a full synthetic 10W30 plus a bottle of Lucas synthetic oil additive, for my events. For off season I will stick with the 5W20.
I had been using Penzoil Platinum 5W20 for all these events. I also did each event on a fresh oil change. The oil held up great. The viscosity was where it should be and it still had life left in it. The only negative was elevated lead levels. Nothing dramatic but something to address. Lead in the oil is a sign of bearing wear or that you're using leaded gas, which I don't normally do. Based on the recomendation of Blackstone I am switching.
For the record I have had the Penzoil Platinum 5W20 tested out of my Explorer V8 after nearly 6K miles and Blackstone recomended I leave it in for another 1K miles. It is great oil for the $. I am using Valvoline in my Cobra now simply because it is cheaper than the Penzoil and I trust the name.
I will post up after my end of July event how the new oil does in analysis.
I had been using Penzoil Platinum 5W20 for all these events. I also did each event on a fresh oil change. The oil held up great. The viscosity was where it should be and it still had life left in it. The only negative was elevated lead levels. Nothing dramatic but something to address. Lead in the oil is a sign of bearing wear or that you're using leaded gas, which I don't normally do. Based on the recomendation of Blackstone I am switching.
For the record I have had the Penzoil Platinum 5W20 tested out of my Explorer V8 after nearly 6K miles and Blackstone recomended I leave it in for another 1K miles. It is great oil for the $. I am using Valvoline in my Cobra now simply because it is cheaper than the Penzoil and I trust the name.
I will post up after my end of July event how the new oil does in analysis.
5th Gear Member
Joined: Apr 2007
Posts: 3,547
From: The High Country
RE: 5W-20 or 5W-30?
ORIGINAL: Riptide
After 3 HPDE events and getting an oil analysis done every time, by Blackstone Labs. I am going with a full synthetic 10W30 plus a bottle of Lucas synthetic oil additive, for my events. For off season I will stick with the 5W20.
I had been using Penzoil Platinum 5W20 for all these events. I also did each event on a fresh oil change. The oil held up great. The viscosity was where it should be and it still had life left in it. The only negative was elevated lead levels. Nothing dramatic but something to address. Lead in the oil is a sign of bearing wear or that you're using leaded gas, which I don't normally do. Based on the recomendation of Blackstone I am switching.
For the record I have had the Penzoil Platinum 5W20 tested out of my Explorer V8 after nearly 6K miles and Blackstone recomended I leave it in for another 1K miles. It is great oil for the $. I am using Valvoline in my Cobra now simply because it is cheaper than the Penzoil and I trust the name.
I will post up after my end of July event how the new oil does in analysis.
I had been using Penzoil Platinum 5W20 for all these events. I also did each event on a fresh oil change. The oil held up great. The viscosity was where it should be and it still had life left in it. The only negative was elevated lead levels. Nothing dramatic but something to address. Lead in the oil is a sign of bearing wear or that you're using leaded gas, which I don't normally do. Based on the recomendation of Blackstone I am switching.
For the record I have had the Penzoil Platinum 5W20 tested out of my Explorer V8 after nearly 6K miles and Blackstone recomended I leave it in for another 1K miles. It is great oil for the $. I am using Valvoline in my Cobra now simply because it is cheaper than the Penzoil and I trust the name.
I will post up after my end of July event how the new oil does in analysis.
That makes me think that for a DD, 5w20 is acceptable.
5th Gear Member
Joined: Jul 2007
Posts: 4,897
From: TX
RE: 5W-20 or 5W-30?
I've been using 0w-30 since mysecond oil change (first was with 5w-20). The car has run noticably smoother and cooler with 30w so I'm sticking with it. Steeda, Saleen and Roush all recommend 30w in their supercharged applications. I think theyhave the experience as towhat worksbest for the 4.6 modular (without getting into Ford's CAFE issues and such). If 30w was killing the engine due to lubrication issuesbecause of tightclearances it would happen much sooner in a FI application I would think...