diff --git a/include/cantera/transport/GasTransport.h b/include/cantera/transport/GasTransport.h
index 4cb78e2372..705243847c 100644
--- a/include/cantera/transport/GasTransport.h
+++ b/include/cantera/transport/GasTransport.h
@@ -148,7 +148,7 @@ class GasTransport : public Transport
                                         double* bstar_coeffs,
                                         double* cstar_coeffs, bool actualT) override;
 
-    void init(ThermoPhase* thermo, int mode=0, int log_level=0) override;
+    void init(ThermoPhase* thermo, int mode=0, int log_level=-7) override;
 
     bool CKMode() const override {
         return m_mode == CK_Mode;
@@ -541,7 +541,8 @@ class GasTransport : public Transport
     //! Quadrupole polarizability
     vector<double> m_quad_polar;
 
-    //! Level of verbose printing during initialization
+    //! Level of verbose printing during initialization.
+    //! @deprecated To be removed after %Cantera 3.1.
     int m_log_level = 0;
 };
 
diff --git a/include/cantera/transport/IonGasTransport.h b/include/cantera/transport/IonGasTransport.h
index d1d2114551..63c081d409 100644
--- a/include/cantera/transport/IonGasTransport.h
+++ b/include/cantera/transport/IonGasTransport.h
@@ -40,7 +40,7 @@ class IonGasTransport : public MixTransport
         return "ionized-gas";
     }
 
-    void init(ThermoPhase* thermo, int mode, int log_level) override;
+    void init(ThermoPhase* thermo, int mode, int log_level=-7) override;
 
     //! Viscosity of the mixture  (kg/m/s).
     //! Only Neutral species contribute to Viscosity.
diff --git a/include/cantera/transport/MixTransport.h b/include/cantera/transport/MixTransport.h
index a328a5b7fd..f881d050de 100644
--- a/include/cantera/transport/MixTransport.h
+++ b/include/cantera/transport/MixTransport.h
@@ -147,7 +147,7 @@ class MixTransport : public GasTransport
                           size_t ldx, const double* const grad_X,
                           size_t ldf, double* const fluxes) override;
 
-    void init(ThermoPhase* thermo, int mode=0, int log_level=0) override;
+    void init(ThermoPhase* thermo, int mode=0, int log_level=-7) override;
 
 protected:
     //! Update the temperature dependent parts of the species thermal
diff --git a/include/cantera/transport/MultiTransport.h b/include/cantera/transport/MultiTransport.h
index be7e5828ac..1ae2da793e 100644
--- a/include/cantera/transport/MultiTransport.h
+++ b/include/cantera/transport/MultiTransport.h
@@ -100,7 +100,7 @@ class MultiTransport : public GasTransport
     void getMassFluxes(const double* state1, const double* state2, double delta,
                        double* fluxes) override;
 
-    void init(ThermoPhase* thermo, int mode=0, int log_level=0) override;
+    void init(ThermoPhase* thermo, int mode=0, int log_level=-7) override;
 
 protected:
     //! Update basic temperature-dependent quantities if the temperature has
diff --git a/include/cantera/transport/Transport.h b/include/cantera/transport/Transport.h
index 98594a3833..df03a1713b 100644
--- a/include/cantera/transport/Transport.h
+++ b/include/cantera/transport/Transport.h
@@ -413,8 +413,10 @@ class Transport
      * @param mode    Chemkin compatible mode or not. This alters the
      *                 specification of the collision integrals. defaults to no.
      * @param log_level Defaults to zero, no logging
+     * @deprecated The `log_level` parameter is deprecated and will be removed after
+     *     %Cantera 3.1.
      */
-    virtual void init(ThermoPhase* thermo, int mode=0, int log_level=0) {}
+    virtual void init(ThermoPhase* thermo, int mode=0, int log_level=-7) {}
 
     //! Boolean indicating the form of the transport properties polynomial fits.
     //! Returns true if the Chemkin form is used.
diff --git a/include/cantera/transport/TransportFactory.h b/include/cantera/transport/TransportFactory.h
index 5ed5f406ab..a4dcff2d94 100644
--- a/include/cantera/transport/TransportFactory.h
+++ b/include/cantera/transport/TransportFactory.h
@@ -54,16 +54,22 @@ class TransportFactory : public Factory<Transport>
      *  @param model     String name for the transport manager
      *  @param thermo    ThermoPhase object
      *  @param log_level log level
+     *
+     *  @deprecated The `log_level` parameter is deprecated and will be removed after
+     *      %Cantera 3.1.
      */
-    Transport* newTransport(const string& model, ThermoPhase* thermo, int log_level=0);
+    Transport* newTransport(const string& model, ThermoPhase* thermo, int log_level=-7);
 
     //! Build a new transport manager using the default transport manager
     //! in the phase description and return a base class pointer to it
     /*!
      * @param thermo    ThermoPhase object
      * @param log_level log level
+     *
+     * @deprecated The `log_level` parameter is deprecated and will be removed after
+     *     %Cantera 3.1.
      */
-    Transport* newTransport(ThermoPhase* thermo, int log_level=0);
+    Transport* newTransport(ThermoPhase* thermo, int log_level=-7);
 
 private:
     //! Static instance of the factor -> This is the only instance of this
diff --git a/include/cantera/transport/WaterTransport.h b/include/cantera/transport/WaterTransport.h
index 74b17c1f77..d5f3ebde95 100644
--- a/include/cantera/transport/WaterTransport.h
+++ b/include/cantera/transport/WaterTransport.h
@@ -57,7 +57,7 @@ class WaterTransport : public Transport
      */
     double thermalConductivity() override;
 
-    void init(ThermoPhase* thermo, int mode=0, int log_level=0) override;
+    void init(ThermoPhase* thermo, int mode=0, int log_level=-7) override;
 };
 }
 #endif
diff --git a/src/transport/GasTransport.cpp b/src/transport/GasTransport.cpp
index ab13ea5e77..ca6bc9c7bd 100644
--- a/src/transport/GasTransport.cpp
+++ b/src/transport/GasTransport.cpp
@@ -29,7 +29,7 @@ void GasTransport::update_T()
 {
     if (m_thermo->nSpecies() != m_nsp) {
         // Rebuild data structures if number of species has changed
-        init(m_thermo, m_mode, m_log_level);
+        init(m_thermo, m_mode, m_log_level != 0 ? m_log_level : -7);
     }
 
     double T = m_thermo->temperature();
@@ -263,6 +263,12 @@ void GasTransport::init(ThermoPhase* thermo, int mode, int log_level)
     m_thermo = thermo;
     m_nsp = m_thermo->nSpecies();
     m_mode = mode;
+    if (log_level == -7) {
+        log_level = 0;
+    } else {
+        warn_deprecated("Transport::init", "The log_level parameter "
+            "is deprecated and will be removed after Cantera 3.1.");
+    }
     m_log_level = log_level;
 
     // set up Monchick and Mason collision integrals
@@ -372,7 +378,7 @@ void GasTransport::setupCollisionIntegral()
     // initialize the collision integral calculator for the desired T* range
     debuglog("*** collision_integrals ***\n", m_log_level);
     MMCollisionInt integrals;
-    integrals.init(tstar_min, tstar_max, m_log_level);
+    integrals.init(tstar_min, tstar_max, m_log_level != 0 ? m_log_level : -7);
     fitCollisionIntegrals(integrals);
     debuglog("*** end of collision_integrals ***\n", m_log_level);
     // make polynomial fits
diff --git a/src/transport/IonGasTransport.cpp b/src/transport/IonGasTransport.cpp
index 3cd12608e9..5867cd870a 100644
--- a/src/transport/IonGasTransport.cpp
+++ b/src/transport/IonGasTransport.cpp
@@ -23,6 +23,12 @@ void IonGasTransport::init(ThermoPhase* thermo, int mode, int log_level)
         throw CanteraError("IonGasTransport::init",
                            "mode = CK_Mode, which is an outdated lower-order fit.");
     }
+    if (log_level == -7) {
+        log_level = 0;
+    } else {
+        warn_deprecated("Transport::init", "The log_level parameter "
+            "is deprecated and will be removed after Cantera 3.1.");
+    }
     m_log_level = log_level;
     // make a local copy of species charge
     for (size_t k = 0; k < m_nsp; k++) {
diff --git a/src/transport/MMCollisionInt.cpp b/src/transport/MMCollisionInt.cpp
index 90b421b947..ae4a21a38d 100644
--- a/src/transport/MMCollisionInt.cpp
+++ b/src/transport/MMCollisionInt.cpp
@@ -215,6 +215,12 @@ double MMCollisionInt::cstar_table[39*8] = {
 
 void MMCollisionInt::init(double tsmin, double tsmax, int log_level)
 {
+    if (log_level == -7) {
+        log_level = 0;
+    } else {
+        warn_deprecated("MMCollisionInt::init", "The log_level parameter "
+            "is deprecated and will be removed after Cantera 3.1.");
+    }
     m_loglevel = log_level;
     debuglog("Collision Integral Polynomial Fits\n", m_loglevel > 0);
     m_nmin = -1;
diff --git a/src/transport/MMCollisionInt.h b/src/transport/MMCollisionInt.h
index 6fd2323a99..00f87bfe18 100644
--- a/src/transport/MMCollisionInt.h
+++ b/src/transport/MMCollisionInt.h
@@ -33,8 +33,10 @@ class MMCollisionInt
      *  @param tsmax       Maximum value of Tstar to carry out the fitting
      *  @param loglevel    Set the loglevel for the object. The default
      *                     loglevel is zero, indicating no output.
+     * @deprecated The `log_level` parameter is deprecated and will be removed after
+     *     %Cantera 3.1.
      */
-    void init(double tsmin, double tsmax, int loglevel = 0);
+    void init(double tsmin, double tsmax, int loglevel = -7);
 
     double omega22(double ts, double deltastar);
     double astar(double ts, double deltastar);
diff --git a/src/transport/TransportFactory.cpp b/src/transport/TransportFactory.cpp
index f721ca08e0..2589697261 100644
--- a/src/transport/TransportFactory.cpp
+++ b/src/transport/TransportFactory.cpp
@@ -68,6 +68,10 @@ void TransportFactory::deleteFactory()
 Transport* TransportFactory::newTransport(const string& transportModel,
         ThermoPhase* phase, int log_level)
 {
+    if (log_level != -7) {
+        warn_deprecated("TransportFactory::newTransport", "The log_level parameter "
+            "is deprecated and will be removed after Cantera 3.1.");
+    }
     if (transportModel != "DustyGas" && canonicalize(transportModel) == "none") {
         return create(transportModel);
     }
@@ -98,6 +102,10 @@ Transport* TransportFactory::newTransport(const string& transportModel,
 
 Transport* TransportFactory::newTransport(ThermoPhase* phase, int log_level)
 {
+    if (log_level != -7) {
+        warn_deprecated("TransportFactory::newTransport", "The log_level parameter "
+            "is deprecated and will be removed after Cantera 3.1.");
+    }
     string transportModel = "none";
     AnyMap& input = phase->input();
     if (input.hasKey("transport")) {
@@ -110,9 +118,9 @@ shared_ptr<Transport> newTransport(shared_ptr<ThermoPhase> thermo, const string&
 {
     Transport* tr;
     if (model == "default") {
-        tr = TransportFactory::factory()->newTransport(thermo.get(), 0);
+        tr = TransportFactory::factory()->newTransport(thermo.get());
     } else {
-        tr = TransportFactory::factory()->newTransport(model, thermo.get(), 0);
+        tr = TransportFactory::factory()->newTransport(model, thermo.get());
     }
     return shared_ptr<Transport>(tr);
 }
diff --git a/src/transport/WaterTransport.cpp b/src/transport/WaterTransport.cpp
index 2c81e153e5..160ee5661e 100644
--- a/src/transport/WaterTransport.cpp
+++ b/src/transport/WaterTransport.cpp
@@ -7,6 +7,7 @@
 #include "cantera/thermo/VPStandardStateTP.h"
 #include "cantera/thermo/PDSS_Water.h"
 #include "cantera/thermo/WaterSSTP.h"
+#include "cantera/base/global.h"
 
 namespace {
 
@@ -32,6 +33,10 @@ namespace Cantera
 
 void WaterTransport::init(ThermoPhase* thermo, int mode, int log_level)
 {
+    if (log_level != -7) {
+        warn_deprecated("Transport::init", "The log_level parameter "
+            "is deprecated and will be removed after Cantera 3.1.");
+    }
     m_thermo = thermo;
 }