can we replace straight weights with multi grade?

[leroyd92]

knowing that modern vehicles using crazy 0w20 and such are designed to use it, can one assume motors of the 80's to late 90's (or the designs ) can runn thinner oils available now since they are said to be stronger?

on this website ive seen a lot of people substitute 5w30 for 10w30 on an 1985 motor (example) or using 1030 instead of 30 wt.

i have 3 vehicles needing Xw30 oil. one needing 530,the other is 30, the other says 1030.

if i live in an area where morning temp is 80degrees and motorcycles in the sun show 125*f oil temps on the dipsticks at 1pm in the afternoon could i run 1030 in everything ?

im sure im gonna get guff for (use what oem calls for) but im just curious

 

[kschachn]

How do you define a thinner oil? Using a 5W-30 instead of 10W-30?

Also, I don't think an engine has to be designed for 0W-20 (or 5W-20) to use it, nor do I think they are crazy. I use 0W-20 in my ECHO and 5W-20 in my Sienna, neither of which specified 20-weight oil when built. Both run fine on the respective oils.

And the short answer is that both engines will run fine on 10W-30, as they would on 5W-30. Especially in your stated application the XW- portion of the weight is meaningless.

 

[barkingspider]

In AZ, I would buy up all the 10w30 and use it in all 3 vehicles without worry. What vehicle is spec'd for Sae 30? That would be the only vehicle I would pay closer attention to, perhaps shorter oci

 

[leroyd92]

Originally Posted By: barkingspider
In AZ, I would buy up all the 10w30 and use it in all 3 vehicles without worry. What vehicle is spec'd for Sae 30? That would be the only vehicle I would pay closer attention to, perhaps shorter oci


91 chevy 350 tbi with 100k-1030 on cap
97 5.4 tritan f150 expedition-530 on cap.
1985 mercrusier 3.0l- 30wt on cap.

i have 1540 in my mercrusier right now and dont think ill change that, i was just thinking about future blowout sales where i can find 1030 cheap, or, go another route and use 1540 in the 97. i just dont wanna do that if it dont need it. i am noticing more oil consumption with full synthetic 530 in the tritan, whice made me wonder if a change is needed

 

[OtisBlkR1]

wow, a 85 thats a straight grade oil.. cool. Ive not seen that myself before.

 

[440Magnum]

10w30 is a dead grade for the most part. Yes, if you're looking at low-end dino oils, the 10w30 probably has fewer viscosity modifiers, and so is preferable.

But in a high-end name-brand oil, the 5w30 will probably have a better base stock and no more viscosity improvers. Maybe fewer, if its a base stock with a better inherent VI than the 10w30 uses.

Therefore, I'd run 5w30 syn or syn blend in both trucks. Bear in mind that Chevy didn't go roller cam in the 350 until a decade after everyone else did, so a 'high mileage' oil with a little extra ZDDP (or ZDDP replacement) might be worth considering. The cam is mild and at 100k its well broken in, so that shouldn't be a real concern and ordinary Pennzoil or Mobil oils should be fine. Whatever you pick, you could run the same in the Triton 5.4.

In the case of the Mercruiser, it is spec'd for a straight grade because of the duty cycle (high load), iffy cooling in a boat, and the fact that 80s oils *did* need VIIs to get any kind of multigrade rating. If it were mine, I'd run a 5w40 synthetic HDEO like T6, or a 10w30 HDEO blend like T5. Both of those do very well in a high-load environment. I'm not saying run out and dump the 15w40, but given the reasons a single-grade was originally spec'd, a dino 15w40 isn't the best way to meet them. Not bad, but a synthetic 5w40 or blend 10w30 would be better.

 

[fdcg27]

10W-30s in the Ford and the Chev?
Sure.
In the boat?
Maybe not and 15W-40 is probably a good choice for it.
In your climate, you could just use 15W-40 in all three of these engines.

 

[leroyd92]

Originally Posted By: fdcg27
10W-30s in the Ford and the Chev?
Sure.
In the boat?
Maybe not and 15W-40 is probably a good choice for it.
In your climate, you could just use 15W-40 in all three of these engines.


thats kinda what i was thinking.... especially since my first oil change was 1040 with the ford and i had oil consumption, and now im having it with full synthetic 530