My son drove home today from college (about 150 mi) and said that his oil pressure was low and motor didn't sound right. He had just had the oil changed before he left. I checked - there was plenty of oil and the motor sounded fine to me. However, the shop put in Kendall 5-30, when the owner's manual calls for 10-30; 5-30 is approved for 60* and below and it's 90* here today. Car is a 97 Firebird 3800. Should I add some STP or something to bring up the viscosity? He said the oil pressure had never before dipped down to where it was reading.
Oil too thin?
- Thread starter RevGTO
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The only difference between a 5w30 and a 10w30 is a 5w will flow better at a slightly lower temp. Otherwise they're both 30 wts. There might be a slight difference in operating temp viscosity, like 10.4 as opposed to 10.5 for a 10w30 (just an example). Now, unless that particular oil is a 20 wt wearin a 30 wt disguise, then you might have a whole different problem altogether
I've done some research ... Kendall is a Phillips/Conoco brand - it's that "synthetic blend" they market - cst is as you describe - 10.4. Isn't that closer to a 20w base?
The viscosities of 5w30 & 10w30 at operating temperature are too close to tell any real world difference. If your son's car is truly experiencing low oil pressure, & it's full of oil, it's not the 5w30 that's causing the problem.
The oil filter may be the problem. Try installing another filter on the car and see if it helps the issue.
The Motorcraft 5w30 blend UOAs that should
test like his Kendall stays a 30 through 3-4K OCI
so I wouldn't add. Lots of 5-30 do get into 20 by 1500 and that would be a better oil to replenish with Maxlife VSOT.
No on 10.4 being a 20 just look a viscosity chart on this page. But I'd be looking at Motorcraft 5-30 UOA if you want to know how his is likely to be doing. I know GM spec'ed 5-30 for the 3.8 a few years and then went back to 10-30 on 3.8 but this is only one OCI and probably out of there before real summer comes.
test like his Kendall stays a 30 through 3-4K OCI
so I wouldn't add. Lots of 5-30 do get into 20 by 1500 and that would be a better oil to replenish with Maxlife VSOT.
No on 10.4 being a 20 just look a viscosity chart on this page. But I'd be looking at Motorcraft 5-30 UOA if you want to know how his is likely to be doing. I know GM spec'ed 5-30 for the 3.8 a few years and then went back to 10-30 on 3.8 but this is only one OCI and probably out of there before real summer comes.
Conoco oils 5w30 and 10 w30 are both 10.9cst @100c. There is only 2 cst diff at 40c that is 64 and 66cst respectively. 5w30 is fine
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Well, regardless of whether or not the cst of 10w30 or 5w30 is here or there ...your son's ride was sounding funny. 5w30 will shear easier then 10w30 ..and this may have occured. Even if it didn't ..you have noise and low oil pressure. Short of REAL diagnostics on the issue, a step up in viscosity would be a wise, and cheap, test to see if it can be relieved.
Sounds to me like the shop put on a cheesy oil filter that is too restrictive. What did they put on?
my mom's olds 88 with the exact same engine, speced for 10w30, has Motorcraft 5w30 (basically identical to Kendal). It's running fantastic with no noise etc. Switching to 10w30 isn't gonna help; something else is ammiss.
Well, the oil filter is a "Firestone" issue - that's where he had it changed, of course. I listened to it cold this morning and it sounded a little noisy - more like a water pump bearing than an internal engine noise. Maybe that's what he was hearing. I've been running Phillips 5-30 syn blend in my LS1 motor this winter and I definitely notice less idle oil pressure on a hot day compared to GC.
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