pros/cons of changing from recommended 5w30

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Jun 3, 2002
I noticed that some here are changing from the recommended 5w30 wt. oil for their vehicle. Many have fallen in love with the 5w20's and say it is better. Many (with higher mileage vehicles, maybe) say they are moving up to 10w30 oils. Is 5w30 not a good oil (shears more) compared to the other two. What are the pros and cons of moving away from your owners manual recommendation to one of the others. In my case, my engine is running good on 5w30 at 110,000, but no UOA's to compare anything. It leaks a little and I am thinking about a high milage 10W30 oil. Thank you.
I have a 97 Taurus, when the car had 100k on it I took it to the dealer for an oil leak, they fixed the leak and serviced it with 5w20, the gas mileage went up but the oil comsumption did too. The car was speced for 10w30 it now has 10w30 the mileage is less but it doesn't use oil and I feel better about it.
I, personally, do not like dino 5w-30 because of the shearing and my Hotlanta climate. I just bought a Honda Odyssey and will use the Motorcraft 5w-20 based on the UOAs and decide later if a heavier oil is warranted. I will do a comparison of the Mobil 1 0w-20 versus the 5w-30 and see which performs better. For a synthetic like Amsoil, the 5w-30 is very shear stable and not an issue. The Mobil 1 10w-30 is more shear stable than the 5w-30. If using dino, I would go the 10w-30 route with Chevron Supreme, Havoline, or Pennzoil. Where are you located?
I live in mid Michigan. It's a Chrysler minivan four banger. I use regular Pennzoil 5W30. Thinking of going to Pennz. High mileage 10W30 to see if it slows the minor gasket leaks before I resort to some gasket replacements. My last mini went 200,000 miles before I sold it and the engine ran like a top and oil leaks/consumption was nil. This van went to any quick lube available. Thanks
For a synthetic like Amsoil, the 5w-30 is very shear stable and not an issue. The Mobil 1 10w-30 is more shear stable than the 5w-30.
With TriSynthetic this was true, as the 5w30 version of that used to thin out a lot, but with Supersyn I have noticed the 5w30 version does not thin out at all and is just as shear stable as the 10w30. Therefore this makes the 10w30 Supersyn obsolete, in my opinion, since you really have no reason not to choose 5w30 since it will flow better on startup in colder weather. Just look at 3MP's results for 5w30 M1, it held it's viscosity extremely well. It wasn't until after about 8k when it started to thicken up a little bit, but not really by a huge amount (and if anything that oil needs to be a bit thicker anyhow) IMHO, 10w30 synthetics are basically obsolete, since you can get such great performance from 0w30 and 5w30 synthetics instead. [ February 08, 2004, 09:15 PM: Message edited by: Patman ]
Patman, I believe that you are correct. I am trying to get thicker is better and lower spread is better out of my head. 10w-30 is such as a staple in the Deep South USA. I will get WalMart to export all the Mobil 0w-30 to the Great White North since it collects dust downhere. Doitmyself, The 5w-30 in your climate makes a big difference in the dino oil. Stick with the 5w-30 for the winter. I would recommend the Pennzoil High Mileage 10w-30 for the months of May through September. You may also want to consider the AutoRX to help the seals last longer but not with High Mileage oil.
I am not one who has qualms about using 5W30 or the "right" 0W30 year round even in Hotlanta or Dallas or at 6000' and 90º in CSprings. I am, however, open to evidence. Does anyone KNOW (as in empirical data) of increased engine failures or massive wear due to the advent of 5W30? I'm betting the data doesn't support concerns, but I have been wrong before.
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