Northstar V8 and 4T80E questions
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Northstar Engines and System Technical Discussion Discussion, Northstar V8 and 4T80E questions in Cadillac Engine Technical Discussion; I have a couple of questions: My first is, am I supposed to drive my engine hard? For example, step ...
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    STSClint's Avatar
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    Northstar V8 and 4T80E questions

    I have a couple of questions:

    My first is, am I supposed to drive my engine hard? For example, step on the gas and pass people, do WOT twice a month, and take it out on the highway. Or do I drive it like I have been, like a granny (for MPG's, and man does this car get GREAT gas mileage for a V8).

    My second question is, should I flush the coolant every 50,000 miles or is it safe to do it every 100,000 miles?

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    Ranger's Avatar
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    Re: Northstar V8 questions

    Highway driving doesn't do much. At 70 MPH it is still loping along at about 2300 RPM. See the "Full Throttle" article in the Technical Archives at the top of the forum page.

    Change (not flush) your coolant every 2 years.

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    LittleNo is offline Cadillac Owners Fanatic
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    Re: Northstar V8 questions

    This makes me smile had you ever been to Germany? my 98 STS has now 130k miles on it, it has to do 200 kph (125 mph) every day on the Autobahn, WOT at least twice a day and runs great. OK, I had to do the Head Bolt Time-Sert Job 20k miles ago, but that must not be because of the hard usage since many N* have the same problem in the U.S. too. The transmission is still the first and shifts like new. I change the transmission oil every 15k miles and every 30k miles the upper transmission filter.

    Changing the coolant every 2 years is excellent, but every 5 years would be enough, I think.
    98eldo32v and 98eldo32v like this.

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    basscatt's Avatar
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    Re: Northstar V8 questions

    Quote Originally Posted by STSClint View Post
    I have a couple of questions:

    My first is, am I supposed to drive my engine hard? For example, step on the gas and pass people, do WOT twice a month, and take it out on the highway. Or do I drive it like I have been, like a granny (for MPG's, and man does this car get GREAT gas mileage for a V8).

    My second question is, should I flush the coolant every 50,000 miles or is it safe to do it every 100,000 miles?
    ----------------------
    am I supposed to drive my engine hard
    SUPPOSED TO? - NO - can you? - it won't hurt anything -

    Or do I drive it like I have been, like a granny

    some will tell you "driving like a granny" is bad for a Northstar motor -
    consider how many grannies drive Northstar powered Cadillacs - and never have a problem -

    I say drive it NORMALLY - and occasionally - give it a WOT -

    should I flush the coolant every 50,000
    actually - you should CHANGE - NOT FLUSH - the coolant every 3 years -

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    Re: Northstar V8 questions

    Heh, heh............. The Northstar is a happy engine at 120. Hard usage (which is VERY different from abuse) is good for the engine and has exactly nothing to do with a possible head gasket problem due to cylinder block head bolt hole thread failure.

    The WOT sequence, so often misinterpreted and misused, is a technique used for loading the engine (cylinders, pistons, rings) to their maximum design power output, then unloading the engine by forced high speed deceleration, thus forcing the piston rings to shed carbon - the cause of stuck rings and excessive oil consumption (said consumption not due to worn rings, valve seals/guides, cylinder walls, leaks).

    Given its healthy daily use, I'll bet that LittleNo's STS is significantly faster and quieter on acceleration than a city-driven example of the same year/model. It does not need an occasional workout to stay clean and free - it lives that way. His car is the equivalent of a NFL wide receiver as compared to the Miller advertisement couch potato.

    (LittleNo, Do you run a 10W-30 or 10W-40 EURO oil in synthetic or conventional ?)

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    LittleNo is offline Cadillac Owners Fanatic
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    Re: Northstar V8 questions

    Heh, heh............. The Northstar is a happy engine at 120.
    yep, it becomes alive above 4000 rpm but seriously, it really does a good job compared to the modern Audi and Mercedes stuff on the roads (I mean, it's basically a 20 year old engine). The only thing I miss on European roads is a 6-speed automatic.

    I run 5W40 synthetic in all N* over 10 years now. It turned out to be the best compromise for our needs. The difficulties we have here: Many times a trip is not longer than lets say 15 minutes, but within those 15 minutes we need performance. So we often don't have time to carefully warm up the engine before kickin it (of course I do my best, but that's the reality on the roads here). So we need an oil with good performance from the first moment on, even at low temperatures, and on the other side, the oil must handle high temperatures (the N* oil cooler works well at high speeds, but the oil temperatures rises quickly above 200F). The only negative thing I can report about 5W40 is that it tends a bit more to leak from the oil pan gasket and the crankshaft seals. But I can live with that (I simply put in new seals when I had the engine out for the headgasket).

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    Re: Northstar V8 questions

    Unfortunately, we do not get to exercise our engines like that over here (not legally anyway).

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    Re: Northstar V8 questions

    I wish we had a road where we can travel high speed legally.

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    Re: Northstar V8 questions

    Well, yes, I understand it can be annoying never to push it without the risk. But you forget, the Autobahn is not a race track, it's a road for travelling purpose, and therefore it has many rules, so driving is not as easy and relaxing as in the U.S. - particularly as in the south, where you have much less traffic on the roads as we have here. When I was in TX for holliday I enjoyed the relaxed driving :-) You will never find anything like this over here.

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    Re: Northstar V8 questions

    I guess everything has it's price as they say.

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    Re: Northstar V8 questions

    I can second his Autobahn/Texas driving comparisons. When I was stationed in Naples from '67 - '70 we drove the Autostrada from/to Naples - Rome frequently and speeds were 85 - 100 all the way. You keep one constant eye way ahead and the other in the rearview for the Ferrari or Porsche coming up your rear at 130 - a relative closing speed of ~50 mph. Thus the flash-to-pass development. Moving accidents are over a quarter mile long at those speeds - parts everywhere. Drove the Autobahn also, while on leave. A 1965 Chevelle Malibu SS 327/350 was NOT the car to attempt road running at 115 mph. Been there, done that - scared.

    A group of cars can safely travel at 110 mph all day long - as long as their relative speeds remain at 0. When one car breaks out, there's hell to pay - but traveling in a pack at that speed demands constant attention: there's no looking for the cup holder. Imagine the typical blonde in a Toyota blasting down the Autobahn at 120, texting and painting her fingernails while sipping her Starbucks. Only in the USA. (Probably not.....)

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    stoveguyy is offline Cadillac Owners Connoisseur
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    What is upper trans filter? Under side cover? How do u easily change that? Or is it. OT easy to change?

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    Re: Northstar V8 questions

    The "upper filter" he mentioned is buried inside the transmission and can be changed during complete teardown and overhaul. Otherwise, the primary screens take care of the "filter" duties.

    Transmission fluid does not need a "filter" because there's nothing to contaminate it - unless the transmission parts start to disintegrate and then the screens only delay the inevitable.

    Please don't hijack threads.

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    stoveguyy is offline Cadillac Owners Connoisseur
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    Re: Northstar V8 questions

    why did GM put a filter on the 4t65e trans and only a screen on the 4t80e trans? both trans were designed about the same time. maybe by the same department? what type of filter media is in the 4t65e filter? some simple mesh?

  16. #15
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    Re: Northstar V8 questions

    Mesh. They're all screens. The "fluid filter" is an enclosed (in a flat metal box) fine mesh screen labyrinth inside the side cover. It IS called a "filter" but the media is not our normal synthetic or paper pleated affair like an engine oil filter.

    Dug this out of the shop manual............... it takes a GM shop labor rate of 11 hours to replace.

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