Has anyone used 0/5W20 in an old engine?

M119

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I've been thinking about it again and i feel like i want to try it at some point. AEHaas stated that his UOAs were fantastic up to 100k miles when he used PYB 5W20 in his 1994 S600. My engine is basically a third of the M120 engine in the S600 and shares the same dna but i'm sure the oil runs much cooler in mine.

Fuel prices are skyrocketing here and i'm more and more of an hypermiler. I have a very relaxed not to say sedate driving, i always drive on momentum and touch the brakes as little as possible, i also shift at lower rpms nowadays if traffic allows me to. I've been able to improve things even further by slightly over inflating my tires (Michelin Energy Saver) and carefully monitor how they wear, I removed as much dead weight as possible such as tools and useless stuff i used to cary around and i always keep my air filter clean.

60% of my driving is 60/65mph highway at 2500-2800 rpm, 40% is country roads at 1800-2300 rpm. Should my engine feel a little less sluggish and should i notice better mpg compared to the synthetic 5W40 i normally use?

Reasons i want/could try 0/5W20:

- See if i can get better gas mileage.
- See it throttle response is better.
- Unstressed engine, oversquare design (low piston speeds, lower bearing loads?)
- Small displacement, underpowered.
- 5.5L sump, the hottest oil temp i've seen was 90c after an extended italian tune up.
- Bearing clearances and width not different from other engines that use 20 weight oil.

The deterrents:

- My engine doesn't have those new low tension rings, no idea how much it comes into play.
- Very little or no UOAs on similar engines to have enough data.
- Low oil pressure?
- At operating temp 99%, maybe there won't be any difference at all compared to 5W40.
- Old valve steam seals?
- Leaks?

Feel free to give your opinion about this precise case and the relevance of me trying it without starting a thin vs. thick war!
 
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If your engine is still reasonably tight clearance wise then I don't think you'll harm anything trying a 5w20. Eljefino's example of the old Dakota lighting up the oil pressure light with 5W20 probably means its engine is almost done and thicker oil would help prolong it for a bit longer... Hopefully yours isn't near that point!
I think you'll find oil thickness friction losses aren't really significant in mileage for normal driving. Idle less, drive 10km/h slower, coast in N downhills, etc, will help alot more IME.
 
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SR5

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OP, if you really want to try it, then do it. It's your car and you only live once.

If you don't like the 5W20 in there, then just change it out to the thicker stuff, it's not a one way street, you can always change your mind.

Have you tried a 5W30 with GF-5 or GF-6 as a half way step?
 

M119

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OP, if you really want to try it, then do it. It's your car and you only live once.

If you don't like the 5W20 in there, then just change it out to the thicker stuff, it's not a one way street, you can always change your mind.

Have you tried a 5W30 with GF-5 or GF-6 as a half way step?
I am thinking about it. In the US people use 5W30 in their old Mercedes without issues. Someone on benzworld has the same car with more than 200k miles on Mobil 1 5W30 and the engine is very healthy!
 

M119

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I'll probably chicken out and forget about it. I am pretty sure that the oil temp would be ok and far less than in a Mercedes V8 cruising at 120mph on the autobahn but i'll never know without an oil pressure and temp gauge. A few years ago before bitog, i switched from 15W40 to SHU 5W40 (12.8 cSt) on my diesel and freaked out when i saw the drop in oil pressure, even though it was still well within spec.
 
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I run 5w20 in my beat up 300k+ 1992 civic ... 5w30 chevron in at moment cause it was cheap.
Car runs on most anything but is slightly noisier at idle with 5w20.
 

M119

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I run 5w20 in my beat up 300k+ 1992 civic ... 5w30 chevron in at moment cause it was cheap.
Car runs on most anything but is slightly noisier at idle with 5w20.
Did you find the engine more responsive with 5W20?
 

M119

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Just found a fantastic deal of some Elf 5W30 at 10€ per 5L jug, took 3. The specs are SL/CF, A5/B5, WSS-M2C 913-D (don't care about this one). It looks like a pretty stout oil to me with a TBN of 9.1 and high saps. Is the formulation of this type of oil closer to a ressource conserving US ILSAC type oil or the usual A3/B4? What HTHS to expect? @SR5 please don't hesite to chime in. ;)
 
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the oil pumps and oil galleries and bearing clearances of engines from past decades were not designed for today's thin oil. you might be able to run a 5w30 during the cold winter months for a vehicle originally requiring 10w30. I run 0w20 in any engine originally recommending 5w20.
 
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I ran it for a while in a 93 Aerostar with a 3.0L V6. Ford back spec'd the engine to 5W20. Later on my guess was they back spec'd engines to boost sales/production of 5W20 which they were switching over to for CAFE credits at the time for their new vehicles. hide At the time 5W20 was the rage here. After using it a while I realized there was ZERO upside. I was trading off protection for a supposed increase in mpg that I wasn't capable of measuring. I switched back to 5w30 and ran it until I junked the Aerostar due to NY roads taking their toll on it.
 
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Just found a fantastic deal of some Elf 5W30 at 10€ per 5L jug, took 3. The specs are SL/CF, A5/B5, WSS-M2C 913-D (don't care about this one). It looks like a pretty stout oil to me with a TBN of 9.1 and high saps. Is the formulation of this type of oil closer to a ressource conserving US ILSAC type oil or the usual A3/B4? What HTHS to expect? @SR5 please don't hesite to chime in. ;)
HTHS value of 2.9 to 3.5 mPas
 

SR5

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Just found a fantastic deal of some Elf 5W30 at 10€ per 5L jug, took 3. The specs are SL/CF, A5/B5, WSS-M2C 913-D (don't care about this one). It looks like a pretty stout oil to me with a TBN of 9.1 and high saps. Is the formulation of this type of oil closer to a ressource conserving US ILSAC type oil or the usual A3/B4? What HTHS to expect? @SR5 please don't hesite to chime in. ;)
Huzzah! A Ford 913-D oil, one of my favourites.

It starts life as a ACEA A5/B5 full synthetic 5W30, at the thin end of the 5W30 viscosity range for better fuel economy, but not so thin it becomes a 20 grade. Then Ford add more ZDDP (~ 1000 ppm Zinc) for extra wear protection and so hence it's now API SL since it's above the typical SN / SP limit by about 200 ppm. Then Ford up the TBN above the typical A5/B5 level of 8, for a longer oil change interval.

It's a well known Ford oil used around the world (except the USA because it's not SN) for both petrol and light duty diesel engines. Ford Australia use it here, in their imported 5.0L V8 Mustang.

Edit: I would guess HTHS would be at the low end for a 30 grade (same as the viscosity) so
probably around 3.0 +/- 0.1 cP
 
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Tried 0/5W-20 for two years in the Ranger, 4Runner and F150. A few downsides and no benefits. Now we have gone the other direction and seeing what 10w-40 does.
 

pbm

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Did you find the engine more responsive with 5W20?
My 2008 Corolla is spec'd for 5w30 (but Toyota later backspec'd 5w20 I believe). I ran 5w20 syn. only once (with no issues) and it did seem to rev more freely (may have been the placebo effect). I went back to 5w30 because I had it in my stash and all our other vehicles call for 20w). I would of stayed with 20 wt. in the Corolla otherwise.
 
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