I screwed up and changed my oil on my 1999 Mountaineer (v8) using 5w30. Will that hurt it for one cycle or should I change it asap..Thanks

 

I thought 5w30 is the right oil? That is what my '99 Explorer with the v6 SHOC uses. Perhaps a different viscosity oil is recommended for the V8.

 

I think Ford recommends 5W30, but if youre in a hot climate I'm here to tell you the 30 is too light.
I'm looking at an old 71 VW owners manual....it has a graph that shows 30 wt only good to 105 degrees outside. I'm just telling you what the book says guys.
LV Dan....Las Vegas....have you seen how thin that oil is when it's 108 outside?

 

Been using 5w-30 per mfg spec on both our 97 Olds Silly and 98 Exploder SOHC V-6. Both approaching 80K miles, which ain't that much these days.

No oil consumption, no blue smoke, other than design flaws (cam chains) no internal probs.

Run the Whiz out of the Exploder, the Silly gets easier duty. Our summers are 90+ with weeks over 100. Long trips in there two.

If modern 5w-30 weren't no good, I would think I'd have two rattly blue smoke puffers by now.

 

I know the Explorer 4.0L SOHC V-6 calls for 5W-30, but I'm not sure about the 5.0L V-8. It may have called for 10W-30. However, I doubt you'll hurt anything, since they would both flow the same at operating temperature. However, oil is cheap, so if you're uncomfortable, just swap it out for 10W-30. I wouldn't go any thicker than that unless you are in a very hot climate.

 

I have a 1999 Mountaineer myself with the V-8 engine and it has 38,000 and the book specifically stated 5W-30 oil and thats exactly what the ford service centers here in Massachusetts use when you go for oil changes so i take it thats the right oil.

:O)

 

5W-30 Is what Ford Recommends, They actually say you will get slightly better gas mileage! I have a 2000 V8 and it has 5W-30.

 

Yep, I'm in Las Vegas and it'll be over 100 today. My Ford owners manual recommends 5w30 even in the hottest climate. It says to go lighter if you run in extreme cold.

For those that don't know about multi-weight oils and would like to know, there are some miss conceptions about multi-weight oil.

All 30 weights, fixed or multi-, are supposed to have the same viscosity at a certain temperature. I forget what that temperature is, but it is around or over the average internal engine temperature. As most know, the viscosity changes with temperature. So with a cold engine, a 30 weight oil has a thicker viscosity which causes oil flow problems in colder temperatures and makes oil pressure sky rocket on first start-up.

The multi-weight oils are oils that are chemically altered through additives, changing the SLOPE of the change in viscosity vs. temperature. So at a cold temperature, a multi-weight oil, such as a 5w30, has a viscosity similar to a thinner oil like a 5w.

But if the engine gets even hotter, the slope continues almost linearly (up to a point, the oil eventually breaks down). So in a single weight, the slope is sharp. A multi-weight has a flatter slope so that the viscosity stays more constant even if it is cold AND as it heats up. I think most can see that a more constant viscosity is better for an engine cold or hot.

But don't think that a 5w30 will have the same viscosity as a single 30 weight at extreme temps because the multi-weight viscosity is always lower, even if you extend the line out to extreme temperatures beyond an engine's.

I agree that the oil seems pretty thin at hot temps. I think the newer engines are designed for thinner oils. Also, with the wonderful additives in an API-SL rated oil, the viscosity is only one part of an oils ability to limit friction and protect the engine. In fact, Consumer Reports tested a bunch of different motor oils (same weight and API rating, different brands) in some NY cabs for 60,000 miles and found almost NO APPRECIABLE WEAR in almost all of them, independant of brand! The chemicals also extend the oils ability to take extreme temperatures before breaking down.

For engines like the '71 VW (I in fact have a Porsche 914 with the VW Type 4 engine), I would not think of running a 5w30 in the middle of summer. I like to run 10w50 in it. Those air cooled engines can get hot in Las Vegas! I also run an external oil cooler. But this is off the subject.

If anyone has evidence that counters this, please let me know.