Does this Diagram Make Sense?

[ac4000]

This is from the service manual for my '91 Toyota MR2. My understanding is that a 10w30 and a 5w30 have approximately the same weight at operating temperature. The only thing I can figure is that Toyota might be thinking of a worst-case scenario, i.e., one in which the VIIs have worn out and the weight has "returned" to a 5 single-weight versus a 10 single-weight (which wouldn't be a concern with synths or a reasonable OCI). Thoughts?

 

[Pablo]

The chart made sense in about 1970. I always get a chuckle out of those, especially the really busy ones.

 

[jmsjags]

i never understood those charts either. they always say use a 5w at lower temperatures and a 10w at higher, but we all know that a 5w will work at any of those temps.

 

[GMorg]

In '91, VIIs were an issue. These were the day that gave us a reason to keep the "spread" to minimum. I interpret the diagram to say "if it is cold enough, take the chance on 5W30, otherwise stick with 10W30. By the way you can also use 10W40 since it has the back-up in viscosity to cover the inevitable shear."

With todays VIIs, the spread is not an issue.

 

[ac4000]

Good; glad to hear the confirmation. Just wanted to make sure I didn't somehow misunderstand everything when I picked up a big jug of 5w30 a few hours ago.

 

[Chris142]

The owners manual for my 02 Wrangler is simmilar. 5w30 below 20f and 10w30 above 20f............Something like that.

 

[aquariuscsm]

I`d use a synthetic 10W40.

 

[OldCowboy]

If I were going to use a 40 weight, it would be 5W or 0W, not 10W.

 

[rjacket]

Originally Posted By: GMorg
In '91, VIIs were an issue. These were the day that gave us a reason to keep the "spread" to minimum. I interpret the diagram to say "if it is cold enough, take the chance on 5W30, otherwise stick with 10W30. By the way you can also use 10W40 since it has the back-up in viscosity to cover the inevitable shear."

With todays VIIs, the spread is not an issue.


That is some issue! Don't use if the ambient temp is going to be more than around 10c!

 

[Shannow]

Remember that GM once specified no 10W-40 because of VII.

Most of the Japanese manuals look very similar to the one pictured even today, but also include 20W-50 from freezing on upwards...even in a Prius.

 

[Bill in Utah]

Yeah the chart has you NOT running 5w30 in temps above 50f.

Once 5w30 came out I ran it year round (and still do) Personally I think when 5w30 came out it was the only time that an oil change made such a difference that I could notice!

The colder starting over 10w30 was noticeable on those cold days.

I'd not follow the chart. It does not make any sense.

bill

 

[teddyboy]

It was the thinking of the day. My wife at the time bought a 91 Honda Accord. It was one of the earlier cars to call for 5W30. When I told the service writer that I wanted the specified 5W30 she said "that's way too light for this climate" (NC). They wanted me to use a 10W40 or even a 20W50, I "compromised" with a 10W30. Back then if their point had been that the 10W30 had more VII and it wasn't really needed in our climated, it would have been somewhat valid. But the contention was that 5W30 was too light. There obviously was a great deal of misunderstanding about multi-vis oils back then, apparently even among the people who came up with those little charts.

 

[mechtech2]

Those charts must have been approved by some empowered people way back.
Similar ones were very common.
And they don't make sense.
This is a very real cause of myths and misinformation.

 

[rjacket]

Originally Posted By: mechtech2
Those charts must have been approved by some empowered people way back.
Similar ones were very common.
And they don't make sense.
This is a very real cause of myths and misinformation.


They may have made sense at the time based on the expected performance of 5w30. They don't make sense now.

 

[artificialist]

MR2 or MR2 Turbo?

If it had a turbo engine, I would run synthetic 5w40 or 10w40.

 

[ac4000]

Originally Posted By: artificialist
MR2 or MR2 Turbo?

If it had a turbo engine, I would run synthetic 5w40 or 10w40.

I'd definitely use synthetic with a turbo, but this one's got a good ol' 5S-FE with just a hair under 200k miles. It's a tank and I'm pretty sure it can handle almost any oil you throw at it (and even the oil you pour in properly).

 

[CATERHAM]

The chart is typical of the time and makes perfect sense and represents the dino oils of the day.

For my BMW, 5w30 was spec'd up to 50F and 15w40 above 20F.
Now it's BMW 5w30 synthetic for all ambient temp's.

 

[fpracha]

Originally Posted By: Bill in Utah
Yeah the chart has you NOT running 5w30 in temps above 50f.

Once 5w30 came out I ran it year round (and still do) Personally I think when 5w30 came out it was the only time that an oil change made such a difference that I could notice!

The colder starting over 10w30 was noticeable on those cold days.

I'd not follow the chart. It does not make any sense.

bill


Hi Bill, did you notice any improvement in fuel consumption over the 10w30 at the time ?

 

[Shannow]

Probably because as an early adopter, he was quickly testing the next generation of 20 weight oils.

 

[Nickdfresh]

I believe Toyota tended to think their 90's vintage four cyl's tended to shear down oils. Mine is the same except no 10W-40 is listed. A 5w30 would be fine, but of course that's assuming the engine is still pretty tight...